Test2PhysicsSoultions

# Test2PhysicsSoultions - Physics 2306 Fall 2007 Second Exam...

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Physics 2306 Fall 2007 Second Exam Form A 1-4) A solid insulating sphere (radius = r a ) has a total charge + 3q distributed uniformly throughout its volume. A hollow conducting sphere is concentric with the solid sphere and has an inner radius r b and an outer radius r c where r a < r b < r c . A negative charge 2q is on the hollow conducting sphere. 1) What is the charge density on the inner surface of the hollow conducting sphere? A. q/4 π r b 2 B. 2q/4 π r b 2 C. 3q/4 π r b 2 D. 4q/4 π r b 2 E. q/4 π r b 2 F. 2q/4 π r b 2 G. 3q/4 π r b 2 H. 4q/4 π r b 2 2) What is the charge density on the outer surface of the hollow conducting sphere? A. q/4 π r c 2 B. 2q/4 π r c 2 C. 3q/4 π r c 2 D. 4q/4 π r c 2 E. q/4 π r c 2 F. 2q/4 π r c 2 G. 3q/4 π r c 2 H. 4q/4 π r c 2 3) What is the electric potential difference V(r c ) V(r b )?

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A. kq/r a B. 2kq/r a C. kq/r c D. 2kq[1/r a 1/r b ] E. zero F. 2kq[1/r a 1/r b ] G. 2kq[1/r a 1/r c ] H. 2kq[1/r a 1/r c ] 4) If the electric potential difference V(r) V(r a ) for r < r a is V(r) V(r a ) = 3 k q [r 2 /r a 2 1]/2 r a , what is the electric potential difference V(r) V( ) for r < r a ? A. 3kqr 2 /2r a 3 + 9kq/2r a B. 3kqr 2 /2r a 3 + 9kq/2r a 3kq/r b + kq/r c C. 3kqr 2 /2r a 3 + 9kq/2r a + kq/r c D. 3kqr 2 /r a 3 + 3kq/2r a 3kq/r b + kq/r c E. zero F. 3kqr 2 /r a 3 + 3kq/2r a G. 3kqr 2 /r a 3 + 3kq/2r a + kq/r c H. 3kqr 2 /r a 3 + 3kq/2r a 3kq/2r b + kq/r c 5) A positive charge Q is distributed in an insulating sphere. The radius of the sphere is r a . The magnitude of the electric field inside the sphere (r r a ) is E(r) = k Q r 2 /r a 4 . What is the electric potential difference V(r) V(r = 0) for r r a ? A. kQr 3 /3r a 4 B. kQr 2 /r a 3 C. kQr 4 /5r a 5 D. kQr 2 /r a 3 E. kQr 3 /3r a 4 F. kQr/r a 2 G. kQr 4 /5r a 5 H. kQr/r a 2
6) Three Gaussian surfaces (S 1 , S 2 , and S 3 ) overlap each other as shown in the figure below. Four charges (3q, 2q, 4q and 5q) are enclosed within the surfaces at the positions shown in the figure. Which one of the following statements is true? A. The electric flux through S 3 is q/ ε 0 . B. The electric flux through S 3 is 5q/ ε 0 . C.

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## This note was uploaded on 04/02/2008 for the course PHYS 2306 taught by Professor Ykim during the Fall '06 term at Virginia Tech.

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Test2PhysicsSoultions - Physics 2306 Fall 2007 Second Exam...

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