4B_SP10_con07_27

# 4B_SP10_con07_27 - Physics 4B Spring 2010 Conference 7...

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Physics 4B Spring 2010 Answers: 1. 1.06 mA, 2. 7.5 7 10 - × A, 3. (a) 0.108 V/m, (b) 7 6.42 10 s 2 yrs × , 4. (a) 4 R , (b) R /16, 5. 19 2.3 10 × , 6. (b) CV Conference # 7 - Current, Resistance, Power 1. (Ch. 27 Exercise 7) The electron in a hydrogen atom moves in a circle of radius 5.3 x 10 -11 m at a speed of 2.2 x 10 6 m/s. What is the average current? 2. (Ch. 27 Problem 5) A nonconducting disk of radius a = 25 cm has a uniform surface charge density σ = 8 μ C/m 2 . It rotates at angular velocity ω = 3 rad/s as depicted in Fig. 27.16. What is the current passing through a surface perpendicular to the plane of the disk? 3. (Ch. 27 Exercise 4) A 30-km length of electrical transmission cable made of copper wire of diameter 1 cm carries a 500-A current. The resistivity of copper is 8 1.7 10 m - × Ω⋅ and the free electron density is 8.5 x 10 28 m -3 . Find (a) the electric field within the wire (b) how long it takes for a given electron to travel the length of the wire. 4.
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## This note was uploaded on 11/17/2010 for the course PHYC 93456 taught by Professor Afdsadsf during the Spring '09 term at City College of San Francisco.

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