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Unformatted text preview: Reilly (mar3978) homework 05 Turner (56725) 1 This printout should have 12 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 (part 1 of 2) 10.0 points A charged mass on the end of a light string is attached to a point on a uniformly charged vertical sheet of infinite extent. The acceleration of gravity is 9 . 8 m / s 2 and the permittivity of free space is 8 . 854 10 12 C 2 / N m 2 . 4 . 6 c m . 1 C 1 g A r e a l c h a r g e d e n s i t y . 2 4 C / m 2 Find the angle the thread makes with the vertically charge sheet. Correct answer: 7 . 87394 . Explanation: Let : g = 9 . 8 m / s 2 , = 8 . 854 10 12 C 2 / N m 2 , m = 1 g = 0 . 001 kg , = 0 . 24 C / m 2 = 2 . 4 10 7 C / m 2 , q = 0 . 1 C = 1 10 7 C , and L = 40 . 6 cm = 0 . 406 m . The length L of the string is superfluous. Let the tension in the string be denoted by T . The electric field due to the infinite sheet is constant in the xdirection and is vector E = 2 . In the and directions, force equilibrium tells us T sin = q 2 T cos = m g tan = T sin T cos = q 2 m g = arctan parenleftbigg q 2 m g parenrightbigg = arctan bracketleftbigg (1 10 7 C) (2 . 4 10 7 C / m 2 ) 2 (0 . 001 kg) (9 . 8 m / s 2 ) bracketrightbigg = 7 . 87394 . 002 (part 2 of 2) 10.0 points What value would in order for he angle 84 ? Correct answer: 16 . 5112 C / m 2 . Explanation: From the previous part, we know = 2 m g tan q = 2 (0 . 001 kg) ( 9 . 8 m / s 2 ) tan(84 ) 1 10 7 C (8 . 854 10 12 C 2 / N m 2 ) 10 6 C 1 C = 16 . 5112 C / m 2 . 003 10.0 points Two large, parallel, insulating plates are charged uniformly with the same positive areal charge density + , which is the charge per unit area. The permittivity of free space = 1 4 k e ....
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This note was uploaded on 11/30/2010 for the course PHY 60230 taught by Professor Turner,j during the Spring '10 term at University of Texas at Austin.
 Spring '10
 TURNER,J

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