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Unformatted text preview: Kapoor (mk9499) oldhomework 10 Turner (60230) 1 This printout should have 13 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points A small electrically charged object is sus pended by a thread between the vertical plates of a parallelplate capacitor. The acceleration of gravity is 9 . 8 m / s 2 . A B vector E + E 200 mg 13 nC =20 4 . 3 cm What is the potential difference between the plates? Correct answer: 2 . 35965 kV. Explanation: Let : m = 200 mg = 0 . 0002 kg , g = 9 . 8 m / s 2 , d = 4 . 3 cm = 0 . 043 m , = 20 , and q = 13 nC = 1 . 3 10 8 C . A B vector E + E m q d The forces acting on the particle are the tension T on the thread, the weight mg and the electric force q E = q V d . Since the par ticle is in equilibrium, the resultant force is equal to zero; i.e. , T sin = q V d T cos = mg Dividing, tan = q V mg d V = mg d tan q = (0 . 0002 kg) (9 . 8 m / s 2 ) (0 . 043 m) 1 . 3 10 8 C tan 20 = 2 . 35965 kV . 002 (part 1 of 2) 10.0 points A 6 . 57 F capacitor is first charged by being connected across a 30 V battery. It is then disconnected from the battery and connected across an uncharged 4 . 83 F capacitor. Find the charge on the 6 . 57 F capacitor. Correct answer: 113 . 592 C. Explanation: Let : C 1 = 6 . 57 F , C 2 = 4 . 83 F and V = 30 V . Kapoor (mk9499) oldhomework 10 Turner (60230) 2 The initial charge of each capacitor is Q 1 = C 1 V , and Q 2 = 0 ....
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This note was uploaded on 06/28/2009 for the course PHY 303L taught by Professor Turner during the Fall '08 term at University of Texas at Austin.
 Fall '08
 Turner
 Physics, Charge, Work

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