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Unformatted text preview: ..__I . PHYSICS 205 - FINAL EXAM 1. What is the ratio of the wavelengths of a 200 eV photon and a 200 eV
electron? '2. Five equal charges Q are equally spaced on
a semicircle of radius R. Find the force on
a charge q locatedas shown. 3. Three concentric spherical thin conducting shells have radii a < b < 0.
Initially the inner shell is not charged, the middle shell has a positive
charge *t Q and the outer shell has a negative charge —Q. Find the electric
potential of the three shells. 4. Design a network of capacitors that has a capacitance of 2 nF and a
breakdown voltage of 400 V using as many 2 nF capacitors that have
individual breakdown voltages of 100 V as needed. '0 (a F l i'g'fL )\ initially uncharged. a)What is the initial If
. I; . The capacitors in the circuit shown are ﬁlm? ' \ battery current when the switch is closed. 5”: b)What is the battery current after a long time. / . N
c) What are the final charges on the ca pacrtors? I Q _Q_ ll__—.— 50V . A metal bar of mass M, resistance R
and length L rides on a pair of long
frictionless perfectly conducting rails that
are inclined so that they make an angle 8
with the horizontal. The rails are
connected to a battery V.
The bar is released from rest in the
presence of a vertical magnetic ﬁeld B.
Describe the subsequent motion.
Find the final value of the current. 7. A series LRC circuit is driven at a frequency of 500 Hz. An oscilloscope
measurement determines the phase angle between current and voltage to be 75° . IfR=3SQ and L=0.15 H, Find C. 8. An X—ray undergoes scattering by a stationary free electron and emerges
with a wavelength of 0.2 nm at an angle of 100° . What is the kinetic
energy of the scattering electron? 9. What is the radius of 56Fe nucleus? 10. Find the binding energy per nucleon of 7Li . 11. The neutron decays into a proton. Write the equation for this decay.
What the energy released in this decay? Where does this energy go? 12. The counting rate of a radioactive source is 8000/5 at t=0. 10 min later ' the rate is 1000/5. What is: a) The half life, b) the decay constant and
c) the count rate at t=30 min? atomic mass of (atomic mass units) 7Li = 7.016004 ‘11 = 1.007325
neutron = 1.008665
electron = 0.000548 1 amu = 931.5 Mews2 August 1996. ...
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- Spring '09