Problem+Set+7!!!!!


 * Alright, two questions posted. Let's get the rest of them up there by Friday (M. Grdinic)**


 * 1. List the four fundamental forces in nature and explain which are relevant to the structure of an atom.**

gravity - negligible on the atomic scale electromagnetism - electrons are negatively charged and protons are positively charged strong force - holds the protons and neutrons of a nucleus together weak force - responsible for radioactive decay/changing neutrons into protons (Marielle Billig)

The fact that a nucleus with all its protons exists should be troubling from your understanding of charges from last year. This was an issue with the scientists of the time as well: how can positive charges stick together? The strong force is the answer. It's a powerful force but one that only works at very short distances. (M. Grdinic)

(Marielle Billig)
 * 2. Draw the field lines for a Hydrogen-1 atom. What happens as they get farther apart. Draw energy bar diagrams.**

3. **How can the Bohr/Quantum mechanical atomic model account for the distinct colors emitted by a given gas as an electric current passes through?** The Quantum mechanical model says that when electrons undergo "jumps" between "levels" (the Bohr model says this), energy is released. The electric current that passes through the gas will cause this release of energy from the atoms. Because different wavelengths of electromagnetic energy carry different amounts of energy, this would explain the various colors that are represented by a discrete spectra of light that an element releases. (Andrew Blank)

There are different types of light, and even thought we can see the visible light coming off of the lamp, and we can only see things and perceive them due to an abundance of photons hitting our eyes. Our eyes notice this in the form of a straight line, but we cannot notice one photon at a time or the particle form of light. The act of observing your environment is photons hitting your eyes. You can't see what makes you able to see, just like you can't see your own eyes without a mirror. (Edward Kang)
 * 4. Take a look at the light coming out of the lamps in this room. Science has now shown that this light streaming to our eyes in packets called photons. Explain why we do not notice this particle nature of light.**

Don't forget that a single photon is incredibly small. Remember that all energy is quantized in terms of //Planck's constant:// a very small value.


 * 5. Explain why doesn't the Uncertainty Principle apply to us as we walk around this planet?**

We cannot apply the Uncertainty Principle to people walking on the Earth because the scale is significantly different. With atoms, electrons are constantly moving at extremely high velocities. Therefore, it is a lot more difficult to determine where they are. If we were to observe people walking on the earth, we could figure out position and velocity. Also, people stop walking. Our eyes can determine whether or not a person is moving. There is no uncertainty of where a person is on the Earth. In addition, when we observe people, we are not changing their position or velocity as opposed to when we observe atoms. Everything is about perspective. We cannot determine where an electron will be at a certain time because it is too small for our powers of observation. If there is a higher "power" observing us, and they are much larger, maybe the Uncertainty Principle will apply to them as well. It is all about perspective and observation. (Jeremy Chin)

You're very close here Jeremy. Be sure to remember that these quantum effects only apply to atomic and subatomic matter due to how we **make** the observations. At the atomic level, the act of observing is no longer a passive process.


 * 6. Explain how the //Photoelectric Effect// relates to energy being quantized**

The photoelectric effect means that shining a blue or ultraviolet light on a sheet of metal will dislodge some electrons, causing a small charge to build up or flow in the metal. The explanation of the photoelectric effect involves assuming light is made up of tiny little packets, or photons, of energy. The Quantization of energy means that energy can only exist in certain steps, nowhere in between. Since a light is energy, and a single photon is a single packet of energy, a photon is a quantized bit of energy. (Matthew Kabelitz)

Determinism is the theory that acts of will, nature, and society are determined by previous events and natural laws. Quantum mechanics allows for a non-deterministic universe to exist. The uncertainty principle states the limitations of the accuracy of our ability to measure. When combining this factor with the fact that quantum mechanics uses probability to estimate observations, it is evident that main factors of quantum mechanics prove to deny determinism. This also goes along with the debate between free will vs. determinism, as quantum mechanics reveals the randomness of events in the universe. (Arin Kerstein)
 * 7. What is //determinism?// Explain what quantum mechanics does to this philosophy.**

Although still debatable, QM does seem to render determinism false at the atomic level. Whether that can be applied to the actions of big, clunky things such as humans remains to be seen. (M. Grdinic)