High energy electrons and hydrogen(protons) A Level Physics Question

[thomas49th]

Hi the question I am asking help for can be found here

http://www.hinchingbrookeschool.net/science/documents/A_GCE_Physics_B_2864_01_January_2007_Question_Paper.pdf

page 13. question 11b and 11c. Page 12 will give you the experiment setup

b - Can somehow please explain how that little widdle in the graph shows electrons are being defracted?

c - Not a clue. Guessing it's about up, down quarks but that's about it :\

Thanks :)

 

[thomas49th]

anybody?

 

[nlightner]

b - The graph shows a pattern of peaks and troughs, which indicates the presence of diffraction. Diffraction is the bending of waves as they pass through an opening or around an obstacle. In this case, the high energy electrons are being diffracted as they pass through the slits in the metal foil. The peaks and troughs in the graph represent the constructive and destructive interference of the diffracted electrons as they pass through the slits.

c - The experiment is actually measuring the diffraction of electrons off of the protons in the metal foil. Protons are made up of three quarks - two "up" quarks and one "down" quark. The electrons are interacting with the protons through the electromagnetic force, which is responsible for the diffraction pattern observed. So in a sense, it is about the up and down quarks, but more specifically it is about the interaction of electrons with the protons in the metal foil.