“How do Laser Interferometers work?”
Laser Interferometers work as follows: A coherent laser beam will be emitted from a source. The beam will then hit a mirror at an angle to its wave of propagation, causing it to split into parts parallel and perpendicular to the original travel. These will be reflected by mirrors, and will head back to the original mirror where they will combine and interfere. This new wave will travel to a detector, where the interference pattern will be picked up and can be analyzed to measure small displacements.
How ‘Invisible Wires’ Could Improve Solar Cell Efficiency
“How can we solve the silicon wire reflectivity problem in solar cells?”
We know that PV modules have a transmission wire reflectivity problem. But some research coming out of Stanford University could change this entirely. Instead of relying upon wires to channel electrons away from the silicon semiconductors, what if we were to use gold sheets with holes in them, and tiny silicon towers on top to redirect sunlight away from the gold sheet and into the holes? This way the maximum amount of sunlight can be absorbed and reflectivity can be minimized. This is just a small example of How ‘Invisible Wires’ Could Improve Solar Cell Efficiency.
Image Credit https://news.stanford.edu
Why Los Angeles is Painting its Streets White
“Why is the City of Angels painting its streets white?”
Something very exciting and innovative is happening right now in my hometown of Los Angeles. To combat climate change, the city is starting to paint some of its streets white. Since the lighter color will reflect more sunlight, less heat will be trapped on the streets, causing local temperature levels to drop up to 10 degrees Fahrenheit (5.5 degrees Celsius) and lessening the need for energy-intensive HVAC systems!
What happens when two lenses are placed together?
“How do we solve a physics problem with two lenses placed together?”
When doing a geometric optics problems, we often assume the lenses to be discrete from one another. However, what happens when we have two lenses right next to each other? Well, let’s think about it using our mathematical mindset. If we look carefully, then we will notice that the same amount of light will be incoming and outgoing for both sides. This is similar to how the voltage drop on two parallel resistors is the same. So what if we were to treat our optical system in a similar manner? Well, after much research into this matter, opticists have shown that both lenses can be replaced with an equivalent lens with a focal length given by the equation 1/f_combined=1/f1+1/f2.
“How does a mirror that bends inwards behave?”
Mirrors come in all different shapes and sizes. Some are straight like a piece of paper, some bend outwards, some inwards. However, what are some of the defining physical characteristics of mirrors? Well, let’s analyze it with our scientific mindsets. When an object is beyond the center of curvature, then an image real, inverted, and minimized will be produced. If the object is at the center of curvature, then a real inverted image of equal size will be produced. If the image is between the center length and focal point, then an image real, inverted, and magnified will be produced. If the object is at the focus, then the image will form at – infinity. And if the object is just beyond the focal point, then a magnified virtual image will be formed. Concave mirrors have numerous applications, ranging from the headlights of cars to shaving mirrors and even to visual bomb detectors!
“What happens when light rays from a reflective or refractive material do not converge?”
When light bounces from some materials, sometimes it does not completely converge. An example can be light incident on planar mirrors or negative lenses. However, an image still forms, contradicting the theory of real images. How can this be? Well, let’s use our scientific mindset to find out. We know when non-parallel light rays do not converge in real space, they are at an angle with each other. However, if we are to think “outside of the box” and move into the virtual world, we can observe that such rays originate from a common point. And since our brains are not advanced enough to distinguish between optical illusions and reality, we will see what scientists call a virtual image at that point. Since virtual images do not exist in reality, they can not be projected onto a screen like real images.
How to make a hologram
“How can we use physics to make a hologram?”
Most photographs are composed in two dimensions. However, wouldn’t it be really cool if we could have three-dimensional photographs? Well, instead of just imagining it, let’s apply our engineering mindset to build it. To begin, let’s start off with a few tools, a laser, some lenses, a beam splitter, mirrors, and holographic film. Next, let’s point the laser to the beam splitter to divide the beam into two separate parts. Next, let’s direct both of these beams through diverging beams so they begin to “spread out”. Let’s also make sure that one of these beams (Called the “object” beam) envelops an object of our desired choice. The light impinging on this object will then be reflected, and let’s make sure that this light is directed onto a piece of holographic film. Let’s then use mirrors to guide the second beam of light (Called the “reference” beam) onto the mirror as well. The holographic film will capture the phase difference between the two beams, as well as the levels of darkness and light resulting from the reflection of the object. After all of this work, we would have just created our very own hologram! This process must be so precise that even vibration on the order of a ninth of the wavelength of the laser would destroy the image!
“How can we create an artificial image of an object using light?”
As human beings, we are very visual creatures. We like to watch movies on big screens, take photographs of memorable events, and look at the stars of our universe using telescopes. Interesting enough, all of these technologies use one vital physical phenomena for their operation, real images. When light from an object passes through a thin concave lens, it will be focused onto a single point. At that single point, an image of the object will be formed. If placed on a planar surface, then this image will be visible for everyone to see! Real images are usually inverted, and their magnification depends on the distance from the object to the focal length of the lens
“Can we use refraction to make reflection?”
Refraction is a common physical phenomenon, and we know that if light from a denser medium passes into a lighter medium then it will bend further away from the normal angle. However, is it possible that this angle can bend so much that it will actually go back into the incident medium? Well, let’s use our scientific mindset to investigate this question. We know that light passing between two mediums behaves as dictated by snell’s law, or n1sin(1)=n2*sin(2). If we were to arrange this equation to find for 2, we would arrive at 2=sin(n1*sin(1)/n2)-1. Now if we analyze this equation, we can realize that if were to have the ray of light incident at an angle 1such that the output would be 90 degrees, the light would not pass to the other side! Physicists have termed this angle the critical angle and is used heavily in fiber optics, where light is trapped in and passes through a long tube of wire.