Hwk5A-2 - if a = 1 . 0 cm, b = 2 . 5 cm, L = 10 cm, and I =...

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PHYS 153 Term 2, 2008-09 Homework 5A Feb. 23 - 27 Problem 1 The total amount of charge that has entered a wire at time t is given by the expression Q = (20 C) ± 1 - exp ² - t 2 . 0s ³´ (1) where t is in seconds and t 0. (a) Graph Q versus t for the interval 0 t 10 s. (b) Find an expression for the current in the wire at time t . (c) What is the maximum value of the current? (d) Graph I versus t for the interval 0 t 10 s. Problem 2 A hollow metal cylinder has inner radius a , outer radius b , length L , and conductivity σ ( σ =1 / ρ , where ρ is resistivity). The current I is ±owing radially outward from the inner surface to the outer surface. (a) Find an expression for the electric ²eld strength inside the metal as a function of the radius r from the cylinder’s axis. (b) Evaluate the electric ²eld strength at the inner and outer surfaces of an iron cylinder
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Unformatted text preview: if a = 1 . 0 cm, b = 2 . 5 cm, L = 10 cm, and I = 25 A. Problem 3 For the circuit in the ²gure below, what are (a) the current through the 2 Ω resistor. (b) the power dissipated by the 20 Ω resistor, and (c) the potential at point a? 1 - 1 Fig. for Problem 3 + _ 20 Ω 5 Ω 2 Ω 4 Ω 100 V a Problem 4 The switch in the fgure below has been in position a For a very long time. It is suddenly ±ipped to position b For 1 . 25 ms, then back to a . How much energy is dissipated by the 50 Ω resistor? Problem 5 The ammeter in the fgure below reads 3 . 0 A. ²ind I 1 , I 2 , and E . 1 - 2 + _ 50 V 50 Ω 20 μ F 125 Ω a b Fig. for Problem 4 A E _ _ 9 V 3 . 0 A 2 . Ω 3 . Ω 4 . 5 Ω I 1 I 2 Fig. for Problem 5...
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This note was uploaded on 02/03/2010 for the course PHYS PHYS 153 taught by Professor Billmcutcheon during the Spring '09 term at UBC.

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Hwk5A-2 - if a = 1 . 0 cm, b = 2 . 5 cm, L = 10 cm, and I =...

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