EX2 - Version 049 ex2 Keto (58610) 1 This print-out should...

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Unformatted text preview: Version 049 ex2 Keto (58610) 1 This print-out should have 9 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points Given: A conducting sphere with radius R and charge + Q. A conducting spherical shell with inner radius 2 R and outer radius 3 R and net charge is + Q. Select the electric potential vs radial dis- tance diagram [ V ( r ) function] which describes this situation. + Q + Q 3 R radius 2 R radius R radius 1. r R 2 R 3 R V parenleftbigg kQ 6 R parenrightbigg 2. r R 2 R 3 R V parenleftbigg kQ 6 R parenrightbigg correct 3. r R 2 R 3 R V parenleftbigg kQ 6 R parenrightbigg 4. r R 2 R 3 R V parenleftbigg kQ 6 R parenrightbigg Explanation: + Q + Q 3 R radius 2 R radius R radius 2 Q on surface- Q on surface Q on surface The charge on the inner sphere is + Q. The net charge on the spherical shell is the sum of the charges on its surfaces + Q. The charge on the inner surface of the spherical shell is the opposite sign of the charge on the inner sphere- Q. The charge on the outer surface of the spherical shell is the net charge on the spheri- cal shell minus the charge on the inner surface of the spherical shell +2 Q. The potential for 3 R < r < is V r = k bracketleftbigg (+ Q ) + (+ Q ) r bracketrightbigg Version 049 ex2 Keto (58610) 2 = + k bracketleftbigg 2 Q r bracketrightbigg , so V 3 R = k bracketleftbigg 2 Q 3 R bracketrightbigg = k Q bracketleftbigg 4 6 R bracketrightbigg = 4 k Q 6 R , and for 2 R < r < 3 R, V r = V 3 R = V 2 R { inside a conductor } V 2 R = 4 k Q 6 R , and for R < r < 2 R, V r = k bracketleftbigg (+ Q ) r + (- Q ) 2 R + (+2 Q ) 3 R bracketrightbigg = k Q bracketleftbigg 1 r + (- 3) + (4) 6 R bracketrightbigg = k Q bracketleftbigg 1 r + (1) 6 R bracketrightbigg , V R = k Q bracketleftbigg 1 R + (1) 6 R bracketrightbigg = k Q bracketleftbigg (6) + (1) 6 R bracketrightbigg = 7 k Q 6 R , and for < r < R, V r = V R = V { inside a conductor } V = 7 k Q 6 R . The potential within a conductor is con- stant and the electric field within a conductor is zero. 002 10.0 points Consider two concentric spherical conducting shells. The inner shell has radius a and charge q 1 on it, while the outer shell has radius 3 a and charge q 2 on it....
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This note was uploaded on 10/06/2010 for the course PHY 316 taught by Professor Markert during the Fall '10 term at University of Texas at Austin.

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EX2 - Version 049 ex2 Keto (58610) 1 This print-out should...

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