Wednesday, July 10, 2013

Your Computer Has a Waveform

A projector for us to see the demonstration of light acting like a particle
"If he do break the smallest particle", he might have to deal with what we learned about today (Julius Ceasar). The morning was spent in lecture. The first subject was wave particle duality. We have been talking about light mostly as a wave so far. We have used it wavelength to calculate things in the diffraction lab. We have looked at its interference with itself. However, it can also act as a particle. Our teacher demonstrated this by having light interact with a charged surface, causing it to give off electrons. This was noticeable because the two formerly charged sheets were no longer repelled from each other. our teacher then told us about the history of wave-particle duality. I enjoyed learning how the theory evolved.

An expansion on the theory was that anything could have a wave form. They tested this with electrons, since electrons are quite tiny. If electrons can act as waves, then they should be able to diffract. Penn has a lot of cool devices. We used a cathode ray tube to shine a beam of electrons through a crystal lattice. Sure enough, it diffracted. We then moved on to talking about Planck's  constant. This number explains the relationship between energy and frequency. It is incredibly interesting. The lecture continued to talk about all kinds of aspects of the theory.

The screen of the electron beam device
After all this lecture, we had a guest speaker, Bob Johnson. He sequences DNA. Since DNA is so long, it is hard to sequence it quickly and with accuracy. The method he talked about involves sucking the DNA through a pore with an electric field. The disturbances are different as different bases pass through the pore. This allows the disturbances to be measured, and hence the bases, much faster than other methods. Overall, I thought that the concepts were interesting, but the talk was at a more introductory level than I would have liked (I have skipped over the introductory information here).
A side view of the electron beam device

After the guest speaker, I had lunch. After that, we did a lab to see if Planck's constant actually worked. The number is a ratio of energy over frequency, so we measured both variables for a variety of colored LEDs. We had amazingly close data, 7x10-34, while the accepted value is about 6.6x10-34. Today has been one of my favorite days, topic-wise, in class so far. I felt like I learned a huge amount that wasn't taught in my physics class.

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