# Chapter 31 - Chapter 31 Objective Questions 1 Figure OQ31.1...

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Chapter 31 Objective Questions 1. Figure OQ31.1 is a graph of the magnetic flux through a certain coil of wire as a function of time during an interval while the radius of the coil is increased, the coil is rotated through 1.5 revolutions, and the external source of the magnetic field is turned off, in that order. Rank the emf induced in the coil at the instants marked A through E from the largest positive value to the largest-magnitude negative value. In your ranking, note any cases of equality and also any instants when the emf is zero. 2. A circular loop of wire with a radius of 4.0 cm is in a uniform magnetic field of magnitude 0.060 T. The plane of the loop is perpendicular to the direction of the magnetic field. In a time interval of 0.50 s, the magnetic field changes to the opposite direction with a magnitude of 0.040 T. What is the magnitude of the average emf induced in the loop? (a) 0.20 V (b) 0.025 V (c) 5.0 mV (d) 1.0 mV (e) 0.20 mV 3. A rectangular conducting loop is placed near a long wire carrying a current I as shown in Figure OQ31.3. If I decrease in time, what can be said of the current induced in the loop? (a) The direction of the current depends on the size of the loop. (b) The current is clockwise. (c) The current is counterclockwise. (d) The current is zero. (e) Nothing can be said about the current in the loop without more information. 4. A flat coil of wire is placed in a uniform magnetic field that is in the y direction. (i) The magnetic flux through the coil is a maximum if the plane of the coil is where? More than one answer may be correct. (a) in the xy plane (b) in the yz plane (c) in the xz plane (d) in any orientation, because it is a constant (ii) For what orientation is the flux zero? Choose from the same possibilities as in part (i). 31_c31_p893-926

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Chapter 31 5. A square, flat loop of wire is pulled at constant velocity through a region of uniform magnetic field directed perpendicular to the plane of the loop as shown in Figure OQ31.5. Which of the following statements are correct? More than one statement may be correct. (a) Current is induced in the loop in the clockwise direction. (b) Current is induced in the loop in the counterclockwise direction. (c) No current is induced in the loop. (d) Charge separation occurs in the loop, with the top edge positive.(e) Charge separation occurs in the loop, with the top edge negative. 6. The bar in Figure OQ31.6 moves on rails to the right with a velocity v r , and a uniform, constant magnetic field is directed out of the page. Which of the following statements are correct? More than one statement may be correct. (a) The induced current in the loop is zero. (b) The induced current in the loop is clockwise. (c) The induced current in the loop is counterclockwise. (d) An external force is required to keep the bar moving at constant speed. (e) No force is required to keep the bar moving at constant speed. 7.
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## This note was uploaded on 04/03/2012 for the course PHYSICS AN 101 taught by Professor N.a during the Spring '12 term at Clark College.

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Chapter 31 - Chapter 31 Objective Questions 1 Figure OQ31.1...

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