Chapter 31 215 Q31.16 (a) The battery makes counterclockwise current I 1 in the primary coil, so its magnetic field B 1 is to the right and increasing just after the switch is closed. The secondary coil will oppose the change with a leftward field B 2 , which comes from an induced clockwise current I 2 that goes to the right in the resistor. (b) At steady state the primary magnetic field is unchanging, so no emf is induced in the secondary. (c) The primary’s field is to the right and decreasing as the switch is opened. The secondary coil opposes this decrease by making its own field to the right, carrying counterclockwise current to the left in the resistor. FIG. Q31.16 Q31.17 The motional emf between the wingtips cannot be used to run a light bulb. To connect the light, an extra insulated wire would have to be run out along each wing, making contact with the wing tip. The wings with the extra wires and the bulb constitute a single-loop circuit. As the plane flies through a uniform magnetic field, the magnetic flux through this loop is constant and zero emf is
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This note was uploaded on 12/14/2011 for the course PHY 203 taught by Professor Staff during the Fall '11 term at Indiana State University .