Why does a compass not respond when held near a wire carrying alternating current?
a. the field changes direction 120 times a second, which is too fast for the compass needle to respond.
b. the field changes direction 120 times a second, negating any magnetic field there might be.
c. the field changes direction 120 times a second, stripping any free electrons that might affect the compass.
d. the field changes direction 60 times a second, doubling the magnetic field in both directions.