The Rainbow: A Physics Phenomenon

Irmary Ortiz Carlo

What is a rainbow? A rainbow can be defined as an optical and meteorological phenomenon. This phenomenon causes a spectrum of light that appear in the sky when the Sun shines onto droplets of moisture in the Earth’s atmosphere. In other words, a rainbow is an arc of spectral colors that appears in the sky opposite to the sun as a result of the refractive dispersion of sunlight in drops of rain or mist.

It takes the form of a multicolored arc. The arc that is formed is red on the outer part and violet on the inner part. A rainbow spans a continuous spectrum of different colors. The discrete bands are an effect of the human color vision. We can see that the rainbow has a sequence of colors. That sequence is red, orange, yellow, green, blue, indigo and violet.

We can see a rainbow in places like waterfalls or fountains. This effect can be artificially created. If you disperse water droplets into the air during a sunny day, you can create an artificial rainbow. It is very difficult for a person to take a picture of the complete semi-circle of a rainbow in one frame. This would require an angle of view of 84 degrees. For a 35 mm camera, a lens with a focal length of 19 mm or less wide-angle lens would be required to obtain the picture of the complete semi-circle.

You want to know how a rainbow is created? Well, the first step is: the light is refracted as it enters the surface of the raindrop, then is reflected off the back of the drop, and finally is refracted again as it goes out of the drop. The effect is that the incoming light is reflected back over a different range of angles. The most intense light is at an angle of 40–42 degrees. The angle is independent of the size of the drop. But that angle does depend on its refractive index. The seawater has a higher refractive index than the rain water refractive index. That’s why the radius of a 'rainbow' in sea spray is smaller than a true rainbow. The amount by which light is refracted depends on its wavelength, and also depends on its color. Blue light, as we know, has shorter wavelength and that’s why is refracted at a greater angle than the red light. But due to the reflection of light rays from the back part of the droplet, the blue light emerges from the droplet at a shorter angle to the original incident white light ray than the red light do.

A rainbow doesn’t appear at a specific location in the sky. Its apparent position depends on the location of the person that it is observing it and also depends on the position of the sun at that moment. All raindrops refract and reflect the light of the Sun in the same way, but only the light from particular raindrops reaches the spectator eye. This light is what constitutes the rainbow for the person that is observing it. The position of a rainbow in the sky is always in the contrary direction of the Sun with respect to the person that is observing it. The interior of the rainbow is always slightly brighter than the exterior part.

The Persian physicist, Ibn al-Haytham, tries to give a scientific explanation for the rainbow. In his work, he explained the formation of a rainbow as an image, which forms at a concave mirror. If the rays of light coming from a light source that is farther, reflect to any point on axis of the mirror, they form concentric circles in that particular point. When it is supposed that the sun is the light source, the eye of the spectator as a point on the axis of the concave mirror and a cloud as a reflecting surface, then it can be seeing the concentric circles are forming on the axis.

Rene Descartes also made some experiments. He experimented with passing rays of light through a large glass sphere that was filled with water. By taking measurements of the angles that the rays emerged, he concluded that the primary bow was caused by a single internal reflection inside the raindrop. Also he concluded that a secondary bow could be caused by two internal reflections. Descartes supported the conclusion he made with a derivation of the law of refraction and he correctly calculated the angles for the two bows. Rene Descartes explanation about the colors of a rainbow was based on a traditional theory that says that colors were produced by a modification or alteration of white light.

Also Isaac Newton made some experiments about this topic. He demonstrated that white light was composed of the light of all the colors of the rainbow. Newton uses a glass prism to separate into the full spectrum of colors, rejecting the traditional theory that the colors were produced by a modification or alteration of white light. This well known scientist also demonstrate that red light gets refracted less than the blue light. That led to the first scientific explanation of the biggest features of a rainbow.

In conclusion, as you can see a rainbow is a complete physics phenomenon. It is something that involves a lot of physics terms. Many scientists tried to explain it in different ways, but all that ways involves the physics.

Hess Law

Jaleidy Z Hernandez Gonzale

Hess's law was invented by Germain Hess (1802- 1850), a Russian chemist and doctor. He was mostly distinguished by his thermo chemical studies in physical chemistry. Hess’s law states the heat evolved or absorbed in a chemical process is the same whether the process takes place in one or in several steps. This is also called the law of constant heat summation. Hess’s law is particularly based on the principle of conservation of energy, and it can be used to predict energy changes that are not easily measured. It states that the change in energy is not dependent from its path, it is a state function. The amount of energy only depends on the states of the reactants and the state of the products, but not on the intermediate steps. Energy (enthalpy) changes in chemical reactions are the same, regardless whether the reactions occur in one or several steps. The total energy change in a chemical reaction is the sum of the energy changes in its many steps leading to the overall reaction.

Hess law allows the enthalpy change for a reaction to be calculated even when it cannot be measured directly. This can be accomplished using arithmetic operations such as multiplying, dividing, adding, or subtracting. When an equation is multiplied by a constant its ΔH must also be multiplied by the same number. If the equation is reversed, the ΔH must also be reserved. A net equation is led by an addition of chemical equations. If the net enthalpy is negative, then the reaction will be exothermic and will be spontaneous. An exothermic reaction is a process or reaction that releases energy usually in the form of heat. If the ΔH of the reaction is positive, than it is an endothermic reaction. An endothermic reaction is a process or reaction that absorbs energy in the form of heat. Hess law says that enthalpy changes are additive. For example, we want the enthalpy of formation of ethane gas, 2C (gr) + 3H2 → C2H6 (g). We can use the following enthalpies to determine the desired one.

C2H6 (g) + 7/2 O2 (g) → 2CO2(g) + 3H2O (l) ΔH°298 = -1560 KJ/mol (1)

C(gr) +O2 (g) → CO2 (g) ΔH°298 = -393 ½ KJ/mol (2)

H2 (g) + ½ O2 (g) → H2O (l) ΔH°298 = -286 KJ/mol (3)

The desired reaction has 2 moles of C on the left, and multiplication of reaction (2) by 2 will give 2 moles of C on the left. Similarly, we multiply reaction (1) by -1 to give 1 mole of C2H6 on the right and multiply reaction (3) by 3 to give 3 moles of H2 on the left. Multiplication of reactions (1), (2), and (3) by -1, 2, and 3, followed by addition, gives the desired equation. Hence ΔH°298 is [-(-1560) + 2(-393 ½) + 3(-286)] kJ/mol. The procedure of combining heats of several reactions to obtain the heat a desired reaction is Hess’s law.

Michael Faraday

Cristina Alicea Matos

The discovery of new things is based on the need of people of learning. Human mind constantly needs to know new things and this is what has taken so many people to make the most important discoveries of the world.

Michael Faraday was born in 1791. He was part of a poor family in London, but apart from this he was extremely curious, questioning everything, he felt an urgent need to know more. When he was 13, he became an errand boy for a bookbinding shop in London. He read every book that he bound, and decided that one day he would write a book of his own. He became interested in the concept of energy, specifically force. Because of his early reading and experiments with the idea of force, he was able to make important discoveries in electricity later in life. He eventually became a chemist and physicist.

Michael Faraday's greatest work was with electricity. In 1821, after the discovery of the phenomenon of magnetism by the Danish chemist, Hans Christian Orsted, the scientists Humphrey Davy and William Hyde Wollaston tried to design an electric motor, but they failed. Michael, went on to build what he called electromagnetic rotation which is a wire extending into a pool of mercury with a magnet placed inside would rotate around the magnet if charged with electricity by a chemical battery. These experiments and inventions become the foundation of modern electromagnetic technology.

Ten years later he began his great series of experiments in which he discovered electromagnetic induction. He found that if he moved a magnet through a loop of wire, an electric current flowed in the wire. The current also flowed if the loop was moved over a stationary magnet. This was the first transformer, although he used it only to demonstrate the principle of electromagnetic induction and did not realized what it would eventually be used for. In 1832, he reported that the quantity of elements separated by passing an electrical current through a molten or dissolved salt was proportional to the quantity of current passed through the circuit. This became the basis of the first law of electrolysis. He also popularized terminology such as anode, cathode, electrode, and ion.

In 1845 he also discovered the phenomenon that he named Diamagnetism - a very weak form of magnetism that is only showed in the presence of an external magnetic field. This phenomenon can be used for levitation. Faraday also investigated in chemistry, discovering chemical substances such as benzene, inventing the system of oxidization numbers, and liquefying gases.

There’s been a huge contribution of Michael Faraday not only to the chemistry field, but to physics also. He never got defeated just because he was born on a poor family, he wanted something else and he did it. Life is like that, we have to live with what has been given to us, but that doesn’t mean we can’t aspire a lot more, because that is what is going to make us to be different from everyone else.

Learning about magnetic fields

Yurivani Rodriguez Olmeda

In this article we are going to talk about magnetic fields. Magnetic fields are surrounding you and you can’t see them. But they are here with a function, and here you are going to learn about them. First, let’s talk about the beginning of magnetic fields. The Greeks where the first people in discover the magnets. They found them in a region of Asia named as Magnesia. Oersted was the man who discovered that a current produce a magnetic field. There are some materials that have big magnetic properties. Some of them are nickel, iron and cobalt. Those are met as magnets too. In physics we study more profound the magnetic field. It is a region in the space in which an electric charge q is displaced in a velocity v, it suffers the effects of a perpendicular force that is perpendicular and proportional to the velocity as the field, and this force is named magnetic induction.( (F ) ⃗=q(v ) ⃗x B ⃗) A fundamental law that permits us to calculate the magnitude of the magnetic field is the Law of Amper. This law calculates the magnetic field produced by a distribution of currents when they have symmetry and time doesn’t change.∮▒□(→┬(B )• □(→┬dl )= μ˳I). There the first term refers to circulation of magnetic field around a close trajectory and the second member, the term I, is referred to the intensity that crosses a way and the last one, the μ˳ is the magnetic constant of permeability. The length cut in small pieces is equal to:∫▒〖dl=2πr〗If we substitute the equation to find the magnetic field according with the law of Amper, we get:

B(2πr)= μ˳I

B=(μ˳I)/((2πr) )

I don’t know if hear about solenoids. Solenoids are coiled wired in form of prop or spirals where circulate an electric current. When this happened a magnetic field is generated in the solenoid. The lines of the field inside the solenoid are almost parallel distribute uniformly or constant. This indicates that the field inside the solenoid is constant. We can use the law of Ampere to get an expression for the magnetic field inside the solenoid.

∮▒〖B*dl=B* ∮▒dl〗=Bl

The law of Ampere involves a total current passing through the closed area.

∮▒〖B dl=Bl= μ˳NI〗

B= μ˳N/l I= μ˳nI

There n= N/l means the number of laps in units of length. Where n= N/l means the number of turns. Solenoids are important because they can create controlled magnetic fields and can be used as electromagnets.

Another theme about magnetic fields that we have to learn are dipoles. A dipole is a source of magnetic field, with a south pole and a North Pole. The Earth is an example of a dipole. Since opposite ends of magnets are attracted, the north pole of a magnet is attracted to the south pole of another magnet. The Earth's North Magnetic Pole (currently in the Arctic Ocean, north of Canada) is physically a south pole, as it attracts the north pole of a compass. Every magnet as a North and South pole. Michael Faraday created imaginary lines to explain the behavior of the force in the magnetic fields. Those imaginary lines leave the North pole and enters in the South pole. They don’t finish and neither cross each other because they are close. At any point the direction of the magnetic field vector is tangent. In this image we can see the behavior of the imaginary lines of our North and South poles. As you can see our South pole is uprith and the North pole is downward.

We are going to finish this article talking about another theme related with magnetic field is named the law of Faraday. This law was established by Michael Faraday at 1831. There he established that an induced voltage in a closed circuit is directly proportional to the speed at what does the time changes and the magnetic flux that crosses a surface. The emf induce in a circuit equals the rate of change of the magnetic field. In the experiments that these great man realized they conclude that we can induce an emf using a simple wile coil inside a magnetic field. More simple to understand we shall see the equation that describe this meaning that is: ∈=-N dφ/dt . The sign φ describe the flux. The flux is proportional to the magnetic field and the area. (φ=BA) In our physic laboratory we realized a very interesting experiment about this law. In this one we introduce a magnet in coil. And we evaluate the emf produce. When you introduce a magnet with a North pole in a coil there is going to be produce an emf negative and if you remove it form the coil is going to be produce a positive emf. This is because the emf produced try to replace the magnetic flux produced. In the case of the magnet remove is produced a positive emf to reestablish the magnetic flux. Wow…really good!!!

I like the magnets and play with them looking their power of attraction. It was one of my favorite themes in physic’s II class. I hope you learn a little bit of these interesting themes…SEE YOU!!!

Quick introduction to the discovery of Electricity from fire to light

Alexander Collazo

The history of electricity begins whit William Gilbert was Queens Elizabeth I own Physician, his primary scientific work was De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure in which he explained why compasses point north and that the earth itself was magnetic. In 1660, the German Otto von Guericke invented a machine that produced static electricity; this was the first electric generator. Later Stephen Gray discovered the principle of conduction and Charles Francois du Fay discovered the two forms of electricity positive and negative. In 1745, The Leyden jar the original capacitor was invented, at this time electricity was considered a mysterious fluid or force. During the 1750’s Benjamin Franklin discovered that lightning where electricity whit his kite experiment and also invited the lightning rod, because of this electricity was associated with light and the people all over the world where in need of a safer way to light up their homes, because fire has never been a safe way of light. Then in the 1800 Alessandro Volta created the first battery, finally a safe dependable source of energy, its power was measured in volts. Thanks to Michael Faraday the current began, man discovered that he could induce a current by passing a magnet through a wire, generators and motors where based in this principle. During 1879 Thomas Edison was focused in the creation of a long lasting light bulb, Edison’s problem was to find a material that didn’t burn while passing electricity through it. Edison discovered that when passing electricity trough a normal cotton string soaked in carbon it becomes incandescent and doesn’t burn and it glowed. Later Edison designed and crafted the first electric plant and system able to generate electricity and carry it to house. Edison’s pearl street power station was had power enough to light up 5000 light bulbs and had about 85 clients. Then thanks to the creation of alternating current systems the electric age began, wich was revolutionary because electricity could be transported than ever before, while direct current couldn’t transport electricity one square mile alternating current could transport electricity more than 200 miles. From there on the world has growth to be addicted to electricity, also thanks to electricity we have developed technologies that in the pass where known as science fiction, who know what awaits in the future…

Bibliography:

http://inventors.about.com/cs/inventorsalphabet/a/electricity_5.htm

http://en.wikipedia.org

http://www.need.org/needpdf/infobook_activities/IntInfo/Elec3I.pdf

Physicians’ Collaboration in Modern Technology

Frances T. Perez Diaz

I recently got an iPhone, and I wondered how such small device could do so much. It inspired me to look for related information. While in the search I found many interesting novelties and the people to whom we owe such great inventions. Recently the two scientists whose work made possible the development of powerful technology were rewarded with the Physics’ Nobel Prize.

Albert Fert, Frenchman, and Peter Grünberg, German, who were honored together with this prize for the creation of technology capable of reading data from hard disks, have focused their research critically on shrinking data storage systems. If no dedication like the one of these two scientists, MP3 players nor laptops with gigabyte memories could not exist. Borje Johansson, member of Swedish Royal Academy of Sciences, which awards the prize, said: “The MP3 player and iPod industry would not have existed without this discovery.”

Each physicist independently discovered the physical effect of magneto resistance (GMR) in 1988. In a GMR system, very weak changes in magnetism generate much larger changes in electrical resistance. This creates the perfect effect for designing digital memory systems and for making miniature hard disks. The information recorded is encoded in microscopically small magnetized areas, which are registered by a readout head and translated into electric current. Later, changes in electric current make up the 1 and 0 of digital data.

The first GMR readout head was emitted in 1997 and ever since the technology has become standard. The Nobel citation described the discovery as “one of the first real applications of the promising field of nanotechnology”. It added: “Applications of this phenomenon have revolutionized techniques for retrieving data from hard disks. The discovery also plays a major role in various magnetic sensors as well as for the development of a new generation of electronics.”

British physicists have said the award was splendidly deserved, and that GMR was among the most obvious and life-transforming daily applications of basic research in the physical sciences. Ben Murdin, Professor of Physics at the University of Surrey, said: “A computer hard disk reader that uses a GMR sensor is equivalent to a jet flying at a speed of 30,000 kilometers per hour — roughly once round the globe in a single hour — at a height of just one meter above the ground, and yet being able to see and catalogue every single blade of grass it passes over.” Professor Jim Al-Khalili, of the University of Surrey, said: “It’s no good having hard drives that can store gigabytes of information if we can’t access it.

The technology that has appeared thanks to GMR has permitted hard disk sensors to read and write much more data, allowing for bigger memory, cheaper and more reliable computers. GMR is one of those wonderful phenomena from the weird world of quantum physics that has been put to use very rapidly. It involves very thin layers of different magnetic materials and the way they allow tiny electric currents to pass through them.”

Dr Grünberg said: “The development of computers showed in the last years that this was an important contribution.” Dr Fert said of his award: “This is a surprise for me but I knew that it was possible. I knew I was among the many candidates.”

In conclusion the discovery of the GMR, which stands for giant magneto-resistance, has revolutionized the life style of people living in this époque. The technologies developed from these findings have lead to the standardization of communication methods. Vivid examples, that are very common to see on almost everyone’s home, are laptops, MP3 players and more specific the iPhone and iPod I posses. The invention has left astounded scientists and physicists which have done nothing but worship this great innovation. Now it has been showed that it is not correct to give all the credit to the people who composed the iPhone, but also to physicists because without the product of their research this technology wouldn’t have revolutionized the world in every sense of the word.

References

Henderson,Mark. Nobel Prize to men who made iPod possible. Times Online. http://www.times online.co.uk/tol/news/science/article2622998.ece

Physics in Medicine

Nelson Valentin Bravo

Physics research is helping people to live longer, healthier lives. Physics is helping doctors to find new cures for many diseases that are affecting people all around the world. In the past decades physics and medicine are moving forward hand to hand. One of the most familiar examples is the use of X-rays to diagnose and treat diseases and fractures. The branch that has to do with the application of physics into the medical field is Medical Physics. This branch has to do with the diagnosis and treatment of human disease. The development of radiotherapy in the 1930’s first led to the presence of physicist in hospitals on a regular basis. In the 1950’s, the contributions that could be made by physics and engineering became more obvious with the creation of radionuclide techniques and the beginning of instrumentation development.

The most important areas of the contribution of physics in medicine include imaging with x-rays, ultrasound, and magnetic resonance. These three are known as “diagnostic radiology”. Another contribution is the treatment of cancer by ionizing radiation; known as “radiation therapy”. Imaging and treatment with radioisotopes; known as “nuclear medicine” is also an area where physics plays an important role. Finally, “health physics” is the latest category in Medical Physics. Diagnostic radiology, with the tool of X-rays, has created a new beginning in medical imaging to see inside the human body. Today X-rays are used for planar projection as well as to see cross-sectional slices of the body using CT scans. Also Magnetic Resonance Imaging (MRI) has made a tremendous contribution to medicine. MRI scan, which does not involve harmful ionizing radiation, has help tremendously in the diagnosis of different types of cancer, reducing suffering for the patient. Ultrasound imaging is a method of imaging inside the human body through the use of high-frequency sound waves. These sound waves are recorded and displayed as a real-time visual image. Ultrasound is mainly used to determine the condition of a pregnant woman and her fetus. It is also useful for imaging many of the body’s internal organs, like the heart, liver, gallbladder, spleen, pancreas, kidneys and bladder. As a real-time scanning instrument, they can show movement of internal tissues and organs which allow physicians to see blood flow and heart functions that can help to diagnose several heart conditions. Million of expectant parents have seen the first “picture” of their unborn child with pelvic ultrasound examinations.

Radiation therapy or radiotherapy is the use of ionizing radiation to treat or control malignant tumor cells (cancers). Total body irradiation (TBI) is a special radiotherapy technique used to prepare the body to receive a bone marrow transplant. Radiotherapy has also a few applications in non-malignant conditions; however it’s not used very often because of the worries about the risk of radiation-induced cancers.

In nuclear medicine radioactive substances are used to diagnose and treat disease too. Nuclear Medicine imaging tests differ from most other imaging techniques in that these tests provide information about both the structure and functionality of the system being investigated. These studies have several applications in neurology, cardiology, oncology, etc. In diagnosis, radioactive substances are administered to patients and the radiation emitted by these substances is measured usually by a gamma camera which creates an image. In therapy, radionuclides are administered to treat diseases or provide pain relief. For example, administration of iodine-131 is used for the treatment of thyroid cancer. Positron-Emission Tomography (PET) is an imaging technique in nuclear medicine that has given the promise of revealing the presence and mechanism of diseases such as cancer, heart disease and brain disorders like Parkinson and Alzheimer.

Finally, Health Physics is the part of physics that deals with the protection of people and their environment from potential radiation hazards, while still enjoying the benefits of the atom. Health physicists work in a variety of disciplines, including research, hospitals, industry, education, environmental protection, and enforcement of government regulations. It is important for physicist and potential physicist to understand that this branch of science can be an extraordinary tool in the advancement of medicine in order to live better and longer lives.

Heike Kamerlingh Onnes

Karl Anthony Schindler

He was born on September 21, 1853 in the Netherlands. After finishing his secondary school, he entered the University of Groningen and obtaind what would nowadays be considered his Bachellor's Degree the following year. After pursuing more studies, he obtained his doctor's degreee in 1879 with a thesis called "New prrofs of the rotation of the earth." In the meantime he had become a professor's assistant at an institute in Delft, where he then became a professor of experimental physics. In 1094 he founded a large cryogenics laboratory, to which he invited other researchers to share, making him highly regarded in the scientific community. In 1908, he was the first person to liquefy helium. After some more work, using the Joule-Thomson effect, he lowered the temperature to 0.9K, which is less than one degree over absolute zero. It was the coldest temperature reached on earth at the time. In 1911, he conducted electrical analysis of pure metals at very low temperatures. Although other scientists expected the flow of electrons to come to a complete stop and make resistivity infinite at absolute zero, Onnes was one of the few that believed the resistivity would decrease to zero. After conducting an experiment on the resistivity of a column of mercury more than once, he realized his idea was correct and published articles on superconductivity. For this, he received much recognition for his work, including the 1913 Nobel Prize in Physics. There is even a crater on the moon named after him. Apart from all the science, his favorite recreations included his family life and helping those who needed it. Although he enjoyed his work very much, he was not pompous about it. He was a man of great personal charm.

It seems he would be an excellent example to follow for us 'scientists in development,' as he included great humility and humanity with his great mind. Thought cannot be useful to humanity without feeling, since mostly every other human has much feeling and is driven by it.

How light manages disorder

Lace J. Hernandez Cruz

In the absence of disorder, in a radiation passing through a slab of material, energy flows orderly and is distributed among channels defined by the angle of incidence that remains constant as the light propagates through the slab. If the slab is broken up into random pieces, the progression of energy losses its order and lots of energy is scattered back to where it came from. If the disorder is a great one, almost no energy makes it to the other side of the slab.

Experiments at the University of Twente, leaded by Ivo Vellekoop and Allard Mosk, showed evidence that this scattering may be overcome to allow a large fraction of the incident light to pass through opaque matter, as reported in Physical Review Letters. Their experiment was based on measuring how much light is transmitted through a disordered sample. The modes became mixed up and little light emerged. They then tried to sneak the light through by sending it at the sample from different angles and with different phases. After many years of studies, they found out transmission could be increased in this way by almost a factor of 103, confirming their conclusions.

The experiment was performed on samples of disordered zinc oxide particles with average diameter of 200 nm, which strongly scatter light so that the mean free path is only 0.85 μm. Two sets of samples were used-one 5.7 and the other 11.3 μm thick. Light from a laser was first reflected off of a liquid-crystal display, which could be contoured to shape the reflected wavefront, and then focussed onto the samples. The liquid-crystal display had 3816 independently programmable segments that were adjusted to optimize transmission.

At high levels of disorder a phenomenon known as localization sets in and it is much more difficult to find open channels. This happens because the scattering caused by disorder results in destructive interference of propagating waves, causing the light to be stopped in its tracks. In fact, they found out a relation between channels and thickness of the sample, and it is that the number of open channels falls off exponentially with sample thickness for strong disorder.

The perturbation theory, which has been a useful tool among experiments, seems not to work for strong disorder. This is why the new optical experiments are so important. Localization was initially studied in the context of spin diffusion and electron localization, but the additional complication of electron-electron interaction makes experiments hard to interpret.

At random locations and at random frequencies, resonant traps occur that light finds difficult to enter and difficult to escape from. These form the closed channels that almost always reject the light, preventing it from passing through the system. Sometimes, the resonances could be uniformly spaced across the sample and lined up in frequency so that incident light can use them to step from one resonance to another.

Independent of dimensionality and independent of the strength of the disorder, the open-channel/closed-channel result has been shown to be a universal theorem. For weak disorder, the open channels have a more complex structure: they follow a random path between the two sides of the sample rather than acting as chains of localized resonances. As disorder is increased, they reach a final destination without crossing the sample and those connections that remain take a direct route. Nevertheless, we will need further experiments similar to the ones explained here to have a final decision upon this issue.

The Search of the Origin

Frances J. Moreno

What is mass? We can measure mass, but what exactly it is? Where it came from? How many particles exist in an atom? Through the time many physicist and many people spends there life trying to look for this answers. For this reason more than 2000 physicist and engineers of different countries, hundreds of universities and laboratories work together to construct a machine that will provide all of us the answers of these questions, the Large Hadron Collider (LHC). This machine is the world's largest and highest-energy particle accelerator. It was built to make collide protons of 7 TeV of energy per beam, and its main purpose is to find the most evasive particle, known as the “God particle”.

The Higgs Boson or “God’s particle” plays an important role in the explanation of the origin of the mass of other fundamentals particles and elements. This will explain the Relativity Theory and will complete the Standard Model. If the higgs boson exist, physicists will move forward one more step to the search of the Grand Unification Theory, the one who pretends to unify three of the four fundamental forces: electromagnetism, strong nuclear force and weak nuclear force, living behind the force of gravity. It will also explain why the gravity force is weaker in order of magnitude than the other three fundamental forces. Today anyone can be able to observe the higgs boson experimentally, they expect to confirm or refute its existence with the LHC.

The Large Hadron Collider is a huge project and a big engineer work. It is built in a circular tunnel 27 km in circumference at a depth ranging from 50m to 175m. It will work at -271ºC. While the machine is on, the total energy stored in the magnets is 10 GJ. Once or twice a day the protons are accelerated, each of them have an energy of 7TeV, giving a total collision energy of 14 TeV. At this energy the protons moves at about a 99.99% of the speed of light (3 x 108 m/s). It will take less than 90 microseconds to the proton to travel around the ring. The protons will collide in a diameter manner, and will provide an enormous quantity of subatomic energy that will permit to observe some events that occur in the big bang.

This machine also involves a lot of controversy. Some scientists affirm that the functioning of the LHC could produce catastrophic events, not just for the Earth but also to the entire universe. Some of these events involve the formation of black holes, the creation of exotic massive matter, and the formation of magnetic monopoles that will produce a transformation that will induce the proton decay.

The Large Hadron Collider turns to be a big challenge for the physicists and engineers. These people work hard on this machine, to find the answers of many questions that have been in their minds for centuries. They believe that the collision of high energy protons will produce a Higgs Boson, better known as the “Gods particle” and with this and the reproduction of the big bang success they will be able to notify the world what exactly is mass and how many particles can be in an atom.

New NASA Craft, With Infrared Power, Will Map The Unseen Sky

Guillermo J. Torraca Santiago

After twelve years of work, the National Aeronautics and Space Administration, also known as NASA, is planning to launch their new spacecraft, known as Wide-field Infrared Survey Explorer (WISE) into orbit on December 10, 2009. This launch is going to take place at the Vandenberg Air Force Base, located in California. WISE is an infrared satellite that is specially designed to map the skies in the form of infrared, or heat radiation, which is basically the type of radiation of light for most of the stars and other objects that surround our universe. These wavelengths can not penetrate our atmosphere, since they are very far from Earth, which makes it invisible to our eyes. In 1983, this problem was resolved, when the Infrared Astronomy Satellite (IRAS), an infrared spacecraft with a 62-pixel camera, was launched in space. Now, the 4 million pixels WISE is going to replace IRAS, and is expected to bring newer infrared sources, such as brown dwarfs, ultra luminous galaxies, and other objects, like near-Earth asteroids that may cause future harm to our planet. This 320 million-dollar craft, equipped with infrared detectors and a 16-inch telescope has the capacity of not only mapping the entire sky every six months, but it also has the ability to be hundreds of times more sensitive than IRAS. Finally, Dr. Edward Wright, principal investigator for WISE said: “If we don’t find something totally unexpected, I’ll be surprised”.

Source: http://www.nytimes.com/2009/12/08/science/space/08wise.html?_r=1&ref=science

Reject Band Active Filters

Francesca Ríos Miller

A reject band activate filter is a filter that is able to block any potency between a selected interval. To understand this type of filter we have to know some terms like active filters of low pass and high pass, adder, and Butterworth filters. An activate filter is an analog circuit characterized because it has at least one activate component besides of the capacitors and resistances. One of the advantages of this type of circuit is that it produces a response very close to the one we want, making them more effective than passive filters.

Active filters can be design to control the frequency that are going to pass and the ones that not, these frequency is known as cutting frequency. There are four types of active filters: high pass, low pass, band pass, and reject band. Each one of this filters have a specific function that repel or let it pass a wide band determined by the cutting frequency. A high pass filter let pass every frequency greater than it cutting frequency. On the other hand a low pass filter let only pass a frequency smaller than it cutting frequency. These terms are important to understand what a reject band filter is because this filter is a combination of these two basic filters.

Another concept that we should know is the adders. These components are use to join the basics filters and construct the reject band desire filter. An adder is an operational amplifier with negative feedback. The exit of the adder is equal to the negative of the sum of the voltages connected to the inverse entrance multiply by the ratio of the resistance of feedback and the resistance of the entrances:

Vout=-R_f/R_in ∑_(i=1)^n▒〖V_i 〗

where n is the total of entrance of the adder assuming that they all have the same resistance. This concept is the one use to make a reject band filter because the entrances would be the voltages of exit of the low pass and high pass filters. For this reason the filter is designed with the exit of the adder with the desire parameters.

The last concept that we should know is the Buttersworth filter, an activate filter with two poles. The rejected amplitude decline more quickly when it has a greater quantity of poles in the filter, making it to react quick than a pole of one filter. This model is selected also because the response of this filter is closer to the desire response compare to the response of other filters. To determine the cutting frequency we choose the values of the resistance and capacitors to calculate the equation that define the Butterworth filter which is

f_c=1/2πRC

An example of this type of filter is one that is able to pass any frequency smaller than 500Hz and greater than 5kHz. This filter could be designed with three op-amps. The capacitors are fixed to be 33nF for the low pass and high pass filters, to select the desire cutting frequencies which are 500Hz and 5kHz. For the low pass filter can be use a resistance of 10kΩ and for the high pass filter one of 1kΩ. With this values, that were choose with the equation of f_c, the values of R and C required can be determine to make the equality.

To construct this circuit the entrance is connected to two Buttersworth filters, the superior is low pass and the inferior is high pass. The exits of the two filters enter to an adder, which exit is finally the reject band signal. The rejected wide of band is of 500Hz to 5kHz.

Galileo Galilei and Astronomy

Jaime R. Angueira Juarbe

Out of all the physicists that we hear about today, one of the most important and revolutionary to the science we study today was the Italian physicist Galileo Galilei (1564-1642). He was not only physicist; he was also a mathematician, an astronomer, a philosopher, and has been nicknamed as “the father of modern observational astronomy,” “father of modern physics,” and “the father of science.” If it were not for Galileo, we might not have developed modern science the way we up to today.

Galileo was able to improve the function and mechanism of a telescope to further expand his astronomical observations. Utilizing a previous primitive model of the telescope, he was to modify it to zoom up to 30x an upright magnified image. Utilizing this device, he discovered the phases of Venus, Jupiter’s four biggest satellites, and sunspots. AS he observed Jupiter, he saw three fixed stars that crossed Jupiter, which he said were invisible. They were invisible because they could not be perceived by the naked eye. One day he noted that one of them had disappeared, concluding that it was hiding behind Jupiter and that the stars where actually orbiting the planet. He later realized that he had in fact discovered three o Jupiter’s largest satellites (discovering the fourth on a later date). During this time period, it was believed that all heavenly objects circled around the Earth; therefore, this was not accepted by the common public. Galileo was a believer of Coppernicanism, who believed that the sun was the center of the universe and not the Earth. Observing Venus he discovered its phases which he related to the phases of the moon. He was misguided thinking that Venus might be orbiting the Earth or perhaps a double cycle between the Earth and the Sun; either way, he provided facts of observations which greatly helped in the understanding of space.

For some time, he observed Saturn with his telescope and noticed three smaller planets around it. As one disappeared he concluded that they were orbiting it and missing one was behind the large planet, like in Jupiter’s case. However, as he focused further on it, he saw the image of the ring which only confused his previous observation. Besides discovering sunspots, he also observed the moon to learn about its surface. He recorded that its surface was rough and uneven like the earth, referring to its mountains and craters. Into the night sky, he recorded the discovering of many dim stars that were unable to be seen without a telescope, including one which was later discovered to be the planet Neptune of our own Milky Way. He also attempted to measure the diameter of certain bodies in comparison to the sun. He was the first to propose that star were in fact suns. He said that they were not spherically placed around the Earth but instead were randomly aligned throughout the galaxy. He argued that brighter stars were closer suns and dimmer stars were further away. Using this light emission theory he attempted to estimate the distance at which these suns were in comparison to our sun. He noted that some were a few hundred distances away from us while others were up to two thousand distances away. These are very small approximations compared to today’s standards; however, they were much larger than believed at the time and much further away than planetary distances which was an important comparison aspect.

Transformation of Communication

Dimitri F Haacke Loven

Today we use all types of communication, through different types of media, if it is a cell phone, computer, walky-talky, television etc. But have you ever asked yourself where did this all began? What was the first machine or contraption used to communicate? It all began with the first to invent and develop this Gugliemo Marconi. Marconi was an Italian physicist and inventor, succeeding in inventing sending wireless signals over a distance of one and a half miles. He brought the first wireless telegraphy to England where he was granted the world's first patent for a system of wireless telegraphy. He was also later known for bringing about in 1899 he established wireless communication between France and England across the English Channel.

His first work came through merely long and short pulses that through an apparatus could be translated into words like a code. This we can still see now a days, what we also call Morse Code. The Morse Code was devised by Samuel Morse for use in transmitting messages. Letters, numbers, and punctuation are represented by combinations of dots or brief taps of the transmitting keys and also through dashes. Marconi, then later on came to send wireless signals overseas, from Newfoundland, Canada to Cornwall, England. Another known way of communication we still use today and is very effective is the radio. Radio stations transmit information through waves or a frequency what we so call audio frequency signals. These frequencies are emitted at different signals or also known as a carrier frequency, for example having your favorite station be 106.0 Fm, would be 106kHz being emitted. Your antenna receive these signals and turn them into electrical signals an transmit it through your speakers.

One of our biggest entertainments is television, where we can acquire tons of information, and one of the most effective ways of communication to the society. The television is the communication of moving pictures between distant points over wire or by means of electromagnetic waves. The moving pictures on a television screen originates with a television camera which forms an optical image of the scene to be transmitted and then breaks the image down into electrical signals. These signals may be amplified and transmitted directly over a cable or they can even be converted into electromagnetic waves. As we’ve seen before, these electromagnetic waves are transmitted by antennas, like the radio waves, and the y are picked up by receiving antennas and then transmitted to a television that can form the electromagnetic waves into an optical image on our screens.

Through the decades we have seen how our ways of communication have been improving, from single dots or dashes, to just seeing your friend on your laptop! We have innovated many easy ways to communicate ourselves with the use of telephones to wireless use of telephones (cell phones). We can use electromagnetic waves to communicate basically with anything. We have even come to send signals to satellites, to outerspace and beyond. Newer innovations come every day into our modern world of wireless communication, but these are merely modern application of Marconi’s excellent work.

The Photoelectric Effect

Armando Gonzalez

The photoelectric effect, originally observed in 1839, but documented by Heinrich Hertz in 1887, consists on the emitting of electrons when a light source hits a surface. These emitted electrons are called photoelectrons. Phillip Eduard Anton von Lenard observed that that the energy of these electrons was proportional to the frequency. This theory contrasted James Clerk Maxwell’s wave theory of light, a theory that prevailed during this period of 1800’s. Von Lenard’s theory proposed that the energy of the electron was proportional to the intensity and in that case inversely proportional to the frequency. Albert Einstein solved this dilemma by proposing that light is composed of photons rather than waves and that the energy in these photons was equal to the frequency times a constant later called Planck’s constant. This theory granted him his first Nobel Prize in Physics in 1921.

For a photon to eject an electron it needs to reach a certain frequency where it will have enough energy to release an electron. To show this effect, a vacuum chamber needs to be created with the conductive metal at one end and a collector at the other. When a light shines on the metal, the electrons are released and move toward the collector. This creates a current that can be measured. The point at which no electrons make it to the collector is called the stopping potential and can be used to determine the maximum kinetic energy of the electrons. Not all of the electrons will have the same energy; they will be emitted with different energies depending on what metal is being used. Also the type of light in use is a factor since some lights have more frequency than others. The kinetic energy, in other words, is the energy of the particles knocked free of the metal surface with the greatest speed. Some of the uses for this effect include night vision devices, spacecrafts, image sensors, photoelectron spectroscopy and others.

The experimental results of the photoelectric effect are:

-the rate of the ejected electrons is directly proportional to the intensity of the light source

-there exists a minimum frequency for any type of metal at which photoelectrons can be emitted.

-an increase in the frequency of the light source causes the photoelectrons intensity to increase too

-the kinetic energy of a emitted photoelectron depends on the frequency of the light source but not on the intensity as long as it is not very high

-the time for the emission of a photoelectron is very small

-the direction of the electrons depends on the direction of the polarization of the light source

Although the relation between the energy of the electrons and the intensity was not tested until 1915, almost 10 years after Einstein proposed this relation. I think it is amazing how Albert Einstein solved the problem of the photoelectric effect with such a simple statement. By proposing photons or light quanta, he proved wrong a theory that had been used for many years.

The collision of two stars, a new find for Astrophysics

Angel A. Aponte

Astronomers observed a massive explosion last year, in a galaxy located 300 million light years from Earth, this was interpreted as a supernova others already known: the bursting of a white dwarf star-indeed, compact the waste of a star like the Sun that has exhausted its fuel, which has been swallowing gas from a companion star to explode herself.

However, some properties of this SN2006gz scientists raised the suspicion of the Center for Astrophysics Harvard-Smithsonian, and began to investigate further the supernova. The suspicions were well founded, since Malcolm Hicken and his colleagues have discovered that what occurred was SN2006gz titanic flash of the collision and explosion of two white dwarfs orbit twins who were in each other and drew close to colliding.

The trace of hydrogen or its absence in the spectrum of light from the explosion is the first track following the supernova astronomers to catalog the group I-a white dwarf that swallows matter from a companion star to explode-and group II -- and very massive star that collapses short-lived when it consumes its fuel and explodes. In group II is detected traces of hydrogen in group I, as SN2006gz, no.

So, this supernova was in group I, in particular Type Ia, but Hicken and his colleagues, also identified and well marked footprints-carbon and silicon in the field which she wore to the outbreak. The presence of these elements in the layers of matter of white dwarfs that shoot out in the explosion is a key feature predicted in theoretical models of the mechanism of collision and explosion of two of these bodies.

This discovery has been cautiously cosmologists who use the stars of the first group as indicators of distances of the universe. It was with this type of star that was discovered some years ago, the accelerating expansion of the universe, but with the explosion of this white dwarf, indicates that not all stars of the first group are equal, and can induce an error in the measures cosmic distance.

Stephen William Hawking

A beautiful man

Miguel J. Ossorio Laracuente

Stephen Hawking is right now the most intelligence man in the world. Don’t matter his condition, a neuro-muscular dystrophy or Lou Gehrig, he work like a professor and work in investigation about research of theoretical cosmology, quantum gravity and general theory of relativity (Black Holes). He started his studies in Oxford and the he pass to the Cambridge University when started his studies in general relativity and cosmology. In his university career, his illness was going bad, but he finished his studies. In this moment of his life, He says "Although there was a cloud over my future, I discovered to my surprise I was enjoying life in this more than they had before. I started moving in my research". He continues his research and investigations until in the final of the1960s, Hawking and his Cambridge friend and colleague, Roger Penrose, applied a new, complex mathematical model they had created from Albert Einstein's general theory of relativity. Hawking proving the first of many singularity theorems; such theorems provide a set of sufficient conditions for the existence of a singularity in space-time. This work showed that, far from being mathematical curiosities which appear only in special cases, singularities are a fairly generic feature of general relativity. He says that in the black holes the second thermodynamic law is violated and begins the speculation for space-time travels. In 1985, Hawking have another fall with his illness and now he loss his voice and utilized a synthesizer. Not matter with that, He continues and public his first book called Cosmology: A brief history of time. With this book he broke sales record. His book Black holes, baby universes and other essays he post "Science can say that the universe had a beginning must have known (...) many scientists did not like the idea that the universe had a beginning had a moment of creation". In 2004 Hawking propose a new theory about the black holes. According to Hawking, the universe is practically full of "small black holes" and believed that they formed the original material of the universe. He says: "In the classical theory of general relativity [...] the beginning of the universe must be a singularity of density and curvature of space-time infinite. In these circumstances would govern all the known laws of physics (...) The more we look at the universe, we discover that by no means arbitrary but obeys certain well-defined laws that operate in different fields. It seems very reasonable to assume that there is a unifying principle, so that all laws are part of some higher law". Concluding this article, Stephen Hawking is a warrior, facing a tough day to day illness, unable to finish their studies and research and even visited an ad hoc aircraft from NASA and the history of the world; he will stay with the great minds that have lived in this world.

How Solar Panels Work and Their Use

Yeiram Martínez

Solar cells are made of two type of semiconductors. N-Type doped silicon, this type can conduct electricity in a much more efficient way than the regular silicon because they are doped with impurities that have extra electrons. These electrons move freely and flow as a current, this works with a second layer called P-Type semiconductors. This layer attracts electrons because they are doped with impurities that are missing one electron. This two layers allow an electric current to flow if an external energy is applied such as light photons.

Solar panels consist of multiple individual solar cells connected either in series or parallel. Each of these solar cell has a voltage of 0.5V and a current from 100-115mA. To make a solar panel around 28-40 cells are connected together and produce a DC electric output of 12V and 4A.

Solar energy is converted to electricity with the photoelectric effect. When the light comes to contact with the atoms in the P-Type semiconductor, the energy in the light photon is absorbed, this excites the atom and causes the excess electron to be ejected from the atom, this causes an electron flow which creates the current of the cell and the force of the electron across the P/N layers, this creates the voltage of the cell.

Solar arrays consist of multiple solar panels, this panels could be use to power up a house, office or any energy consuming structure. Today there is in the market different systems that store the produced DC electricity in batteries, convert this DC Electricity to AC for home use, and synchronize the voltage produced with the voltage in the grid allowing the produced electricity to enter the energy grid. This causes the electric meter to run backwards. The installation of this system is very expensive but at the long run is beneficial for the owner because they don’t consume electricity. The following image presents a diagram of an arrangement of solar panels connected to a system that was previously explained.

Lightning

Peter H. Meléndez Cardona

Sometimes we see a ray of light between the clouds and we ask ourselves what is that? And how is form? The name of this light is call a lightning and this lightning is a discharge of a large electrostatic charges that builds up on clouds near the surface of the earth during atmospheric disturbances such a thunderstorms. Scientist still doesn’t how the lightning forms they have studied different causes ranging from atmospheric perturbations: wind, humidity, friction, and atmospheric pressure to the impact of solar wind and accumulation of charged solar particles. Ice inside a cloud is thought to be a key element in lightning development, and may cause a forcible separation of positive and negative charges within the cloud and assisting in the formation of lightning.

Some lightning strikes have similar characteristics so scientists have given names to these various types of lightning. The streak lightning is the most common observed lightning. The majority of the lightning occurs inside the clouds so we do not see most of them. The types of lightning are Bead lightning, Ribbon lightning, Staccato lightning, Forked lightning, Ground to cloud Lightning, Cloud to cloud Lightning, Sheet lightning, Heat lightning, Dry Lightning, Rocket lightning, Ball lightning. But also there are positive and negative Lightning, the negative lightning has an average bolt that carries an electric current of 30 kiloampere (kA), and transfers a charge of five coulombs and 500 MJ of energy. Large bolts of lightning can carry up to 120 kA and 350 coulombs. Also the voltage is proportional to the length of the bolt. The positive lightning carries an electric current of 300 kA about 10 times the negative lightning. Lightning rapidly heats the air in its immediate proximity to around 20,000 °C (36,000 °F) almost three times the temperature of the surface of the Sun. This compresses the surrounding clear air and creates a supersonic shock wave, which decays to an acoustic wave that is heard as thunder. Thunder is the sound made by lightning. The louder you hear the thunder is the distance that the lightning is from the person. The lightning produces an increase in the pressure and temperature and this produce a rapid expansion of the air surrounding and within the bolt of lightning. In turn, this expansion of air creates a sonic shock wave, which produces the sound of thunder.

The movement of electrical charges produces a magnetic field. The intense currents of a lightning discharge create a fleeting but very strong magnetic field. The phenomenon of lightning-induced remnant magnetism is where the lightning current path passes through rock, soil, or metal these materials can become permanently magnetized. These currents follow the least resistive path, where faults, ore bodies, or ground water offers a less resistive path. Lightning-induced magnetic anomalies can be mapped in the ground, and analysis of magnetized materials can confirm lightning was the source of the magnetization and provide an estimate of the peak current of the lightning discharge.

Now we can understand what is a lightning and how is form, showing how natures work ways that we will never understand.

Spin Ice: The Monopole Would-Be

Orlando Soto-Cáceres

For decades, physicists have searched for a magnetic monopole. Nevertheless, after so many years of research on has yet to be found. It is common to find magnets that have a north (N) and south (S) pole, but these have never been reported to be separate. This might seem paradoxical, because we can readily find isolated electrical charges such as electrons or ions. In recent years, however, researchers have reported the behavior magnetic monopoles in crystals called spin ice. So are they monopoles or not?

Spin ice crystals are shiny, honey-colored crystals that at first glance, appear to have no particular properties. Put these crystals at really cold temperatures, though, and unusual its unusual characteristics might surprise you. One of these properties is that when cooled nearly to absolute zero, the atomic moments remain in a disordered state, as opposed to the majority of magnetic materials that acquire magnetic order when cooled.

How does this happen? Every atom in a given structure carries with it a magnetic moment, which can be compared to a really small bar magnet. These atomic moments are constantly interacting with each other through their magnetic fields until they line up in order, resulting in the formation of a crystalline structure. In the case of spin ice, the atoms do not acquire the order, but still form the crystalline structure. When these disoriented atoms are in sufficient numbers, they affect the polarization of the crystal, and there is no longer a north or south pole in the structure, but rather in the atoms isolated in space within the crystalline lattice.

Do these “magnetic monopoles” have a charge? In October 2009, Bramwell et al, reported in Nature (journal of scientific research) measuring the force experienced by spin ice’s particles in the presence of a magnetic field. He reported it being approximately 4.6 µB Å-1, a thousand times smaller than that of a “cosmic monopole” - a theoretical monopole whose charge has been calculated by physicists- and that they interact by Coloumb’s law. However, it is important to know that these crystals do not conduct electricity like most metals would, but instead like water. This makes sense, because water is a polar molecule. Therefore, there is no “one charge” to spin ice, but millions of isolated charges entrapped in the crystal.

If it is not a monopole, then what is it? It turns out that although spin ice is not a monopole in itself, due to its inherent quality of containing disoriented atomic moments within it, it is certainly a special kind of material. So special, it can reproduce the effects of a monopole by changes in the interactions and arrangement of atoms. This is particularly interesting because it can give scientists ideas as to how monopoles might originate naturally or of the potential applications of these materials. This means that the search for a real monopole is still on. This makes one wonder: How many more monopolitic materials will be found before encountering the real thing?

Look! No wires!

Jonathan Nieves

On a constantly changing civilization like ours, everyday scientist and production companies are face with the challenge of developing and evolving new technology to fit the ever growing needs and demands of the world and the their consumers. A very well known challenge over the years has been our struggle for more efficient energy supplement. Recently we have entered the age were wireless control over our resources and devices has been a main focus of developers, and more recently several companies have evolved wireless even further with its new wireless electricity technology which brings forth great promise in the field of energy distribution. For a while now, we’ve started seeing several wireless energy devices entering the electronics industries and pushing productivity further. The Powermat by Powermat USA industries is such a device. It enables the charging of electric devices without wires using several physics principals but more importantly magnetic induction. As the device is magnetically attracted to the source in the mat it starts charging the devices. This device is a step forward to easy energy transfer in everyday life, and although very innovated, it is still a long way from the dream of a fully wireless world. Yet discouraged we shall not be for even more recently the dream is closer than ever thanks to the very talented people at WiTricity Corp. They have developed a technology that far surpasses the Powermat and any other electric charging system I’ve seen yet. WiTricity showed that with its new technology it was able to power a 60 watt light bulb from a distance of over 7 feet. An amazing achievement as the energy also go’s over obstacles and reaches its destination receiver. How do they do it? It’s simpler than you might think, or at least if you are acquainted to the basics of physics. WiTricity’s tech uses the very basis of electrical physics understandings. Electromagnetism, Magnetic Induction, Energy/Power Coupling and the most important one, Resonant Magnetic Coupling, all principles that bring forth this great success in the field of energy distribution. WiTricity declared that by making receivers of the device of magnetic materials that bare a resonance to each other they are enable easier energy distribution which not only allows greater distance for the EM waves to travel, but also it makes it so it work specifically on the device they required.

Needless to say this advancement by WiTricity will open new doors for future everyday use of electricity. We could imagine the world fully charge and wireless. No longer would we be limited by the boundaries of limited energy source locations. Scientists have long dreamed of removing the need to constantly need a plug or batteries for electrical devices to work. Since in physics we learn that EM waves can travel far distances this is but maybe but a few years away of being a different story. No more low batteries on cell phones. Being able to whip out your laptops without worrying about needing to plug it in or even whether you have enough charge to finish that report for later. This is just the first steps. Physics always told as that in theory all this is possible, and soon, companies like WiTricity will tell us that it’s no longer theory, its reality.

Contact lenses in physics

Ingrid S. Forestier Román

Lenses have curved surfaces, or a very large number of flat surfaces located at slightly different angles. Converging lenses which are positive lenses are thicker at the centre than at the edges. Diverging lenses which are negative lenses are thicker at the edges than at the centre. Contact lenses go beyond a vision correction. They are very helpful for the eye because by converging or diverging the rays of light that enters the eye they form the image on the retina.

The eye works like a camera with two lenses, absorbing and processing light reflected from your surroundings. Light first passes through the cornea. Like a camera lens, it refracts light, helping to focus the light. The light then passes through the pupil, like the aperture in a camera, the pupil controls the amount of light entering the eye by becoming larger or smaller. The light then passes through the eye's natural crystalline lens. The natural crystalline lens "fine-tunes" the image before it is focused on the retina at the back of the eye. The retina works like the film in a camera. The retinal nerves absorb light and convert it into electrical signals. These signals are subsequently sent through the optic nerve to the brain where they are interpreted as visual images. If both lenses are working properly, the light is focused precisely on the surface of the retina. If the two lenses are not working properly, clear vision may be achieved by refocusing light rays with the use of corrective lenses.

There exist different types of impairments that could be corrected with convex or concave lenses. Myopia is a visual disability where the image of the object seen is formed in front of the retina. In this impairment, one can see objects that are near but those that are distant one cannot. Myopia is a very common impairment that can be corrected by the use of concave contact lenses, lenses that are thinner in the center than on the edges increasing the focal length.. Hyperopia or also known as hypermetropia is where the image of the object seen is formed behind the retina. In this case one can distinguish far objects but the one near appear to be blurred. This defect can be corrected by the use of convex contact lenses, lenses that are thicker in the center than on the edges decreasing the focal length. . Another very common impairment is the astigmatism, it happens when the lens of the eye has more than one focal point. Persons with this visual disability cannot see clearly and detailed, that is why they need cylindrical lenses to correct their impairment. Last but not least is Presbyopia, is an impairment that develop with age because the eye loses its elasticity. Contact lenses used to correct this vision defect are bifocal, bifocal or multifocal lenses have two or more different curves or shapes combined into one lens. Usually the bottom of the lens is for reading or viewing close objects, while the top of the lens is for seeing farther into the distance.

As mentioned before, type of contact lenses used depends on the type of vision impairment one have, and how much refractive error is involved. To know how much the lens bends the light to focus on the retina, Scientifics measured it in diopters (D).

What are electromagnetic waves?

Aurymarie Cerdá Claudio

To know what an electromagnetic wave is, it is necessary to understand and internalize what is an electric field and what is a magnetic field. An electric field is going to be found wherever a charged particle is present; it is a property of this particle. It is the space surrounding the charged particle and it exerts a force on any other charged particle near it. A magnetic field is the space surrounding magnetic materials, and they are detected by the force they exert on other materials, that can interact with them; because if the other material does not has electric charges or particles then nothing could happened.

There are two basic types of charges: positive and negative charges. An atom contains both, protons and electrons which are positive charges and negative charges respectively. Protons and electrons interact with each other and cause the nucleus of that atom to situate in a specific position. If in an atom there were only protons then the nucleus will be always moving, because they interact between them but there is no force to counteract these forces. So it could be raised that like charges repel each other while unlike charges attract each other. A proton and an electron do not “touch” each other they interact because they are electric charged particles so they have both electric fields that are what makes them to interact. Electric charges exert forces to other electric charged particles through electric fields; the same thing happens with the magnetic fields. A magnet has a magnetic field that would interact with another magnetic material near the first one.

The interaction between a magnetic field and an electric field can be explained as follows. When having a flow of electrons each negatively charged particle will produce and electric field. Many electrons moving will then produce many electric fields. Each electric field will produce a magnetic field; of course magnetic materials will be present at this system. The interaction occurs as a consequence of the interaction at elementary particles level.

To explain what an electromagnetic wave is, using a radio antenna would help. When a current of electrons travels along the wire of this antenna an electric field is produced at the antenna. This electric field at the same time produces a magnetic field, that magnetic field creates a new electric field and so on. For this to happen, the first electric field needs to be changing so it can be produced. In this way the electric fields and the magnetic fields are connected to each other; the electric and magnetic fields oscillate and propagate through space forming the electromagnetic wave. The magnetic field and the electric field are considered a phase because they are a repetitive pattern that oscillates perpendicular to each other and they are perpendicular to the energy propagation. The frequency of the oscillations of the electric and magnetic fields the wavelength of the waves determines whether the electromagnetic wave is visible light, ultraviolet light, infrared light, radio waves, X-rays, or gamma rays; known as electromagnetic waves.