[Illustration: FIG. 238.--As long as the coil rotates between the
poles of the magnet, current flows.]
320. A Test of the Preceding Statement. We will test the statement
that a magnet has electric properties by another experiment. Between
the poles of a strong magnet suspend a movable coil which is connected
with a sensitive galvanometer (Fig. 237). Starting with the coil in
the position of Figure 228, when many lines of force pass through it,
let the coil be rotated quickly until it reaches the position
indicated in Figure 238, when no lines of force pass through it.
During the motion of the coil, a strong deflection of the galvanometer
is observed; but the deflection ceases as soon as the coil ceases to
rotate. If, now, starting with the position of Figure 238, the coil is
rotated forward to its starting point, a deflection occurs in the
opposite direction, showing that a current is present, but that it
flows in the opposite direction. So long as the coil is in motion, it
is cut by a varying number of lines of force, and current is induced
in the coil.
|