EXPERIMENT 183. Motion produced with a hollow coil and a piece of iron.
446. Directions. (A) Arrange as in [Fig. 144]. Coil H (No. 90) is to be used as a pendulum, and can be supported by fastening a string to it, the upper end of which should be tied to S W.
Connect the ends of H with K and D C. There will be a slight magnetic field about H as soon as the circuit is closed.
(B) Hold I C near the end of the coil. Close the circuit for an instant. Is there any motion produced in H? While the motion will be slight, there should be enough to be noticed if the cell is strong.
(C) Swing the suspended coil back and forth like a pendulum for a minute, until you get in mind the rapidity of its vibrations. Stop it, then repeat (B), closing and opening the circuit at regular intervals, so that the little impulses given by the attraction for I C will gradually cause H to vibrate. The wires leading from H should not drag upon the table.
EXPERIMENT 184. Motion with hollow coil and bar magnet.
447. Directions. (A) Substitute the bar magnet M (No. 97) for the iron of [Exp. 183] ([Fig. 144]). Get clearly in mind the polarity of the coil from the way the current flows through it, then test it with the compass to find whether you are right.
(B) Hold the N pole of M near the left-hand end of the coil, close the circuit for an instant and study results.