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Unformatted text preview: benavides (jjb2356) homework 16 Turner (59130) 1 This printout should have 10 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points A 0 . 28 F capacitor is given a charge Q . After 1 s, the capacitors charge is 0 . 5 Q . What is the effective resistance across this capacitor? Correct answer: 5 . 15248 M. Explanation: Let : C = 0 . 28 F = 2 . 8 10 7 F and t = 1 s . The charge on the capacitor is Q ( t ) = Q e t/ . e t/ = Q Q t = ln parenleftbigg Q Q parenrightbigg = t ln parenleftbigg Q Q parenrightbigg . The effective resistance is R = C = t C ln parenleftbigg Q Q parenrightbigg = 1 s (2 . 8 10 7 F) ln parenleftbigg Q . 5 Q parenrightbigg 1 M 10 6 = 5 . 15248 M . 002 10.0 points The switch S has been in the position a for a long time. Then at t = 0, it is moved from a to b. C R 1 R 2 E S b a Find the time when the charge in the ca pacitor is reduced to 1 e of its value at t = 0. 1. = 1 R 1 C 2. = R 2 C 3. = radicalbig R 1 R 2 C 4. = ( R 1 + R 2 ) C correct 5. = 1 ( R 1 + R 2 ) C 6. = 2 ( R 1 + R 2 ) C 7. = R 1 + R 2 2 C 8. = 1 R 1 R 2 C 9. = 1 R 2 C 10. = R 1 C Explanation: In charging an R C circuit, the characteris tic time constant is given by = R C , where in this problem R is the equivalent...
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This note was uploaded on 03/26/2012 for the course PHY 303L taught by Professor Turner during the Spring '08 term at University of Texas at Austin.
 Spring '08
 Turner
 Charge, Work

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