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Unformatted text preview: tovar (jdt436) homework 16 Turner (59070) 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 . 15 F capacitor is given a charge Q . After 16 s, the capacitors charge is 0 . 5 Q . What is the effective resistance across this capacitor? Correct answer: 153 . 887 M. Explanation: Let : C = 0 . 15 F = 1 . 5 10 7 F and t = 16 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 = 16 s (1 . 5 10 7 F) ln parenleftbigg Q . 5 Q parenrightbigg 1 M 10 6 = 153 . 887 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. = R 1 + R 2 2 C 2. = ( R 1 + R 2 ) C correct 3. = 1 R 1 R 2 C 4. = R 2 C 5. = 2 ( R 1 + R 2 ) C 6. = 1 R 1 C 7. = 1 R 2 C 8. = 1 ( R 1 + R 2 ) C 9. = radicalbig R 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...
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This note was uploaded on 12/11/2009 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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