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Unformatted text preview: Version One Homework 9 Savrasov 39819 May 15, 2006 1 This printout should have 12 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. The due time is Central time. Changing Magnetic Field 31:01, trigonometry, numeric, > 1 min, nor mal. 001 (part 1 of 1) 1 points A coil is wrapped with 300 turns of wire on the perimeter of a circular frame (of radius 80 cm). Each turn has the same area, equal to that of the frame. A uniform magnetic field is directed perpendicular to the plane of the coil. This field changes at a constant rate from 20 mT to 50 mT in 20 ms. What is the magnitude of the induced E in the coil at the instant the magnetic field has a magnitude of 35 mT? Correct answer: 904 . 779 V. Explanation: Basic Concepts: E = N d B dt B Z ~ B d ~ A = B A Solution: E = N d B dt = N A B t = N r 2 ( B 2 B 1 ) t = (300) (80 cm) 2 (50 mT) (20 mT) 20 ms = 904 . 779 V E = 904 . 779 V . Induced EMF in a Coil 31:01, calculus, numeric, > 1 min, normal. 002 (part 1 of 1) 1 points A 30 turns circular coil with a radius 4 cm and a resistance 1 is placed in a magnetic field directed perpendicular to the plane of the coil. The magnitude of the magnetic field varies in time according to the expression B = a 1 t + a 2 t 2 , where a 1 = 0 . 01 T / s, a 2 = 0 . 04 T / s 2 are constants, time t is in seconds and field B is in Tesla. Calculate the magnitude of the induced E in the coil at t = 5 s. Correct answer: 0 . 0618265 V. Explanation: Basic Concepts: Faradays Law of Induc tion E = d B dt Note: The resistance of the coil is unnecessary when calculating the induced E . The area of the circular coil is: A = r 2 = (0 . 04 m) 2 = 0...
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This note was uploaded on 03/24/2011 for the course PHYS 13843 taught by Professor Dr.andygavrin during the Spring '10 term at IUPUI.
 Spring '10
 Dr.AndyGavrin

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