# Help Understanding Light/Atom Thoeries

1. The problem statement, all variables and given/known data
I am studying for my physics final and I had some questions about the theories we learned in class.

2. Relevant Theories
Relativity

States the speed of light is a constant (c= 3E8 m/s). This was found using the equation E=mc^2.

Brownian Motion

Established the atomic theory which say that atoms movement is random (as the temperature increases, the atom movement increases)

This says that atoms have quantized energy levels (The energy levels is where the electron ‘sits’). When absorbed the electron jumps up and when emitted the electron jumps down.
All atoms give off Electromagnetic Radiation-the wavelength of the radiation depends on the temperature. [Visible Light: blue is the hottest, white is in the middle, red is the coolest]

Photo-Electric Effect

States that light can be viewed as particles. These partials of light are known as photons. A proton is a packet of light energy E=h. Photons release electrons. As photons come in, the photon gives all its energy to an electron, and the electron comes out (Photon in, electron out)

Unstable isotopes have atomic particles that randomly decay over time. Decay relates to the half-life of the isotope. The decay causes biological damage to the cell at an atomic level [Absorbed dose=Energy/mass ; Biological Equivalent Dose(rem)= absorbed dose(in rads)*RBE(Relative Biological Effectiveness)].

Compton Scattering

Mass-less photons have momentum.
Elastic Scattering- energy is conserved before and after an electron scatters.

deBroglie Wavelength

Particles have properties that are similar to waves.

Rutherford Back-scattering

Established the idea that in an atom, the nucleus is a very tiny positive charge while the rest of the atoms ‘space’ or electron cloud is filled with electrons and a lot of empty space.

3. The attempt at a solution
These are the questions I had relating to the theories

deBroglie Wavelength

Besides wavelength and frequency, what other wave properties are used with particles?

[COLOR="rgb(153, 50, 204)"] All I can think of is period and amplitude but I am unsure as to when I would need to use either of them when discussing particles. [/COLOR]

Relativity/Compton Scattering/Photo-Electric Effect

Relativity says that the speed of light was found by using the equation E=mc^2. Compton Scattering says that photons (which are alpha particles[2 neutrons & 2 protons]) are mass-less. The Photo-Electric Effect says that light is made of packets of protons. So if, Energy=mass*speed of light^2, and light is made up of photons which are mass-less, does that mean the speed of light have no energy? [E=mc^2 ; E=(zero)(3E8^2) ; E=zero]

[INDENT]

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Photo-Electric Effect

When it is talking about photons coming in and an electron coming out, that is talking a atom, right?

Just to check and make sure I got this right, when a photon is absorbed, the electron jumps up an energy level (which is some energy level/orbit that is further away from the nucleus) and when a photon is emitted, the electron jumps down an energy level (which is some energy level/orbit that is closer to the nucleus). Electrons can only jump if they have the excact amount of energy to get to the orbit.

[COLOR="rgb(153, 50, 204)"] Just wanted to check an make sure this is correct. [/COLOR]

Rutherford Back-scattering

Is the empty space in the electron cloud "made" of anything or is it just nothing-ness?

Also, in the electron cloud, does the ’empty space’ carry a negative charge as well? Or have any properties?

I know that the electrons are negatively charged. I don’t understand the concept of ’empty space’ because there is a repelling force between electrons and I would have assumed that the forces is being transferred over this ’empty space’; and if there is a force repelling the electrons or attracting the electron to the nucleus, then there can’t be nothing there because the forces are being transferred there. [I might be looking to far into this and confusing myself. :bugeye: ]

Any help/explanation would be greatly appreciated!

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