FINAL_F08_final

# FINAL_F08_final - Physics 213 Your Name: Recitation Section...

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2 1. True/False [10 points, no partial credit] Mark T (True) or F (False) in the space at the right of each statement. (a) The net magnetic flux through any closed surface is always zero. (b) A time-varying electric field can give rise to magnetic field, even if no electric currents are present. (c) A current-carrying wire loop whose plane is perpendicular to a uniform magnetic field experiences zero net force but a non-zero torque. (d) Electric field lines cannot form closed loops. (e) In a series LCR circuit driven by sinusoidal voltage, the amplitude of the voltage across the resistor cannot be greater than the amplitude of the source’s voltage. (f) A loop of wire rotating with constant angular speed in a constant uniform magnetic field generates DC current. (g) Magnetic fields never exert forces on objects with no net electric charge. (h) The units of H F are equivalent to seconds. (j) The amplitude of the voltage oscillations in the standard household AC electrical outlets in North America is 120 V. (k) If an initially empty solenoid is filled with material, the inductance of the solenoid will always increase, no matter what material is used.
3 2-6. SHORT ANSWER [26 points] Write your answers in the spaces provided. 2. [3 points] A small bar magnet is moving at a constant speed in the +x direction, passing through the center of an aluminum ring suspended on a string in the plane perpendicular to the bar magnet’s trajectory. As the magnet passes through the ring, the force experienced by the ring is: (A) In the +x direction, whenever it’s non-zero (B) In the -x direction, whenever it’s non-zero (C) First in the +x direction, then in the –x direction (D) First in the -x direction, then in the +x direction (E) Always zero Answer: 3. [6 points] Two circular wire loops #1 and #2 situated directly above one another carry electric currents I 1 and I 2 in the same sense, as shown. (As seen from the top, both currents circulate counterclockwise.) (a)

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## This note was uploaded on 12/25/2009 for the course PHYS 213 at Cornell.

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FINAL_F08_final - Physics 213 Your Name: Recitation Section...

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