Conceptual Questions Chap. 19

1. Conceptual Questions Chap. 19 No, for two reasons. First, there are wires carrying currents in opposite directions, so the net magnetic field is very small. Second, the current direction is alternating at 60 Hz, so the magnetic field is oscillating at 60 Hz also. This frequency is too fast for the compass to follow, so the effect on the compass reading averages to zero. • Can you use a compass to detect the currents in wires in the walls near light switches in your home? • Can a constant magnetic field set into motion an electron at rest? Why or why not? • Is it possible to orient a current loop in a uniform magnetic field such that the loop will not tend to rotate? Explain. • A magnet attracts a piece of iron. The iron can then attract another piece of iron. On the basis of domain alignment, explain what happens in each piece of iron. No, since a charge at rest is completely unaffected by a magnetic field. Yes, if the magnetic field is directed perpendicular to the plane of the loop, the forces on opposite sides of the loop will be equal in magnitude and opposite in direction in the plane of the loop, which will not cause a net torque on the loop. The magnet causes domain alignment in the iron such that the iron becomes magnetic and is attracted to the original magnet. Now that the iron is magnetic, it can produce an identical effect in another piece of iron.