[Illustration: FIG. 5.--ELECTROMAGNET.]
ELECTRIC MOTOR.
By placing the magnet thus formed upon the motor base, C, in front of
the armature, h, as shown in Fig. 6, and connecting one terminal of
the magnet with the battery and the other with the clamping screw, e,
of the magnet, and by connecting the commutator spring, j, with the
remaining pole of the battery, the motor will be made to rotate
rapidly.
COMPASS AND MAGNETIC EXPERIMENTS.
By placing one end of the bar magnetized by the solenoid near the
compass contained by the cabinet (Fig. 7) it will be seen that one end
of the compass needle is attracted. When the opposite end of the bar
is presented to the same end of the needle, that end of the needle
will be repelled and the opposite one attracted, showing that like
poles repel each other while unlike poles attract.
[Illustration: FIG. 7.--MAGNETIC EXPERIMENT.]
GALVANOMETER.
By placing one of the coils, A, in the block, D, then placing in the
cavity in the top of the block the compass, with the line marked N S
arranged at right angles to the axis of the coil, a serviceable
galvanometer will be formed (Fig. 8). By turning the galvanometer so
that the needle will point north and south without the current
passing, with N underneath one end of the needle, and then connecting
the poles of the battery with the terminals of this galvanometer, a
deflection of the compass needle will be produced, the direction of
which depends upon the direction of the current.
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