Wednesday, July 10, 2013

Testing The Phenomenons of The 20th Century

Physics class is finally progressing to the quantum world! Today, Bill taught us about the beginning of quantum physics - starting with Planck's equation and ending with Heisenberg's Uncertainty Principle. I've read many books about it but actually receiving a lesson from Bill, one of the best science teachers I've met, is much more exhilarating. 

When the intensity, or brightness, of a light-bulb is augmented and its energy and frequency is graphed, the distance between the curves become bigger. Science, at the time, was unable to explain this phenomenon. This trend was apparent in ALL material; it did not matter what material it was. Because of the high energy of the bodies, the energy that the body emits is what enables us to see it, not the light that reflects off of it; this is a black-body. Also, this was a "ultraviolet catastrophe" because the integral of the graph, with higher and higher temperature, would result in INFINITE energy. Truthfully, I'm unsure how this was disproved, I"ll have to ask Bill about it. Max Planck found a relationship and put it in an equation: Energy Radiated = kT^4. This can be related to: Frequency(max) * Temperature = constant. This is all translates to "as temperature increases, wavelength decreases." This means that smaller wavelengths have higher energies. This is completely counter-intuitive and it was a great accomplishment at the time - actually, still now! At this point, the model switched from an entire system to individual waves because we were examining wavelengths.  Through further advancement, we found out that particles act as waves and waves act as particles. This was fundamentally rejected at the time because it could not be mathematically represented. With the mathematical model (that was proven with Planck's equation and another relationship: Change in energy = h(Planck's constant) * Frequency): Frequency x Momentum = Planck's Constant (6E-34, this number is found in nature and is eccentric). This equation fundamentally proved that if an object has momentum, it has a wavelength and if a wave has a wavelength, it has a momentum. Bill used a baseball for an example; it's momentum is so much larger than Planck's constant that its wavelength practically cannot be observed by the human eye since wavelength is inversely proportional to momentum. We also touched on Schrodinger's equation, I didn't quite understand all of it, I'll have to study it more. The concept that I got out of it is that the measurements always have uncertainty and ultimately, as we become better at the accuracy of the position of the object, the measurement of its momentum becomes more inaccurate becomes more inaccurate. In this blog, I wrote a bunch of equations and it seems like I'm just memorizing it but that's completely not true. In class, we examine these relationships and test them with experiments and truly get a feel of what the relationships come down to. Bill's teaching style really puts that idea out there and is helping all the students get a feel of what physics really is.

We found Planck's constant, which is quintessential to proving Planck's relationship, through an experiment. We first set up the oscillator with a circuit connected to an LED. LED's are unique in the fact that they are made of semi-conductors and if the arrangement of the materials is not correct, the apparatus will fail to create the desired light. LEDs convert electrical energy to electromagnetic energy (photons). Meaning that once the circuit is complete, it will disperse light in all directions. However, the unique part of an LED is that it will not light unless a threshold energy level is met. We set up an apparatus with the oscillator spectrometer to measure the voltage that the LED requires and the frequency of the light created by the LEDs. By finding the slope of the graph of these two variables, we found Planck's constant. Our result was 6E-34 Joules-sec, which is incredibly close to the exact value of Planck's constant. Not all of the physics behind the LED is known to scientists right now. They are trying to find the process of the electric-electromagnetic conversion to light and the energy threshold. I'm unsure of what the debate was about, I'll definitely have to consult Bill again!  

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