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Physics 751 Homework #1
Due Friday September 5, 11:00 am.
1.
(a) Suppose the electron in a hydrogen atom is in the circular Bohr orbit with
n
= 30. How many
times per second does it go around?
(b) Suppose now the electron drops to the
n
= 29 state, emitting a single photon. What is the
frequency of this photon, in cycles per second?
(c) Comment on the relation between your answers in (a), (b) above. What would you guess the
relation to be for
n
= 300?
2.
Rutherford established that all the positive charge in an atom was concentrated in a massive
central nucleus by analyzing the scattering of
α
particles, which are He nuclei. He found that the
numbers scattered as a function of angle of deflection were as predicted using a model of a point
nucleus with the usual inversesquare repulsion. Would this be true if the
α
’s actually hit the
nucleus? Find (somewhere) the approximate size of the gold nucleus (he used gold foil) and
deduce what minimum energy of the incoming
α
particle would be expected to show deviation
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This note was uploaded on 12/07/2011 for the course PHYSICS 751 taught by Professor Michaelfowler during the Fall '07 term at UVA.
 Fall '07
 MichaelFowler
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