A lightbulb is plugged into a household outlet, and one of the wires leading to it is wound into a coil. Now a slug of iron is slid into the coil. What effect will this have?
A) The lamp will dim because energy will now be dissipated in the iron.
B) The lamp will get brighter because there will be an induced emf that will drive more current through the lamp.
C) The lamp will dim because a back emf will be produced by the coil, and this will reduce the current flowing in the coil and the lamp.
D) This will have no effect on the brightness of the lamp.
E) This will not affect the lamp's brightness because the coil will shift the phase, but not the magnitude, of the current through the lamp.
C
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