94 



the coil always repel the N pole of the magnetic needle 

 and attract its S pole ? 



2. Slip a thick wire through a piece of paper or card- 

 board and attach the wire to the desk source of electricity. 

 Sprinkle filings lightly on the card, and notice whether they 

 assume any characteristic positions. If so, sketch roughly. 



Have you seen, so far, any respect in which current 

 electricity could not be considered equivalent to a magnet ? 



EXPERIMENT 91. THE PRINCIPLE OF THE MOTOR, OR 

 ELECTRICITY AS A SOURCE OF MOTION 



I. Suspend a lightweight coil of wire (Fig. 71) between 

 the poles of a horseshoe magnet. Does the coil assume 

 any characteristic position, or will it 

 ^ Ar remain where placed ? 



2. Connect the terminals of the coil to 

 an electric battery and note the result. 



Since current flowing through a coil 

 transforms the coil into a magnet for 

 the time, can you suggest why the coil 

 moved ? Why did the coil finally come 

 to rest ? 



3. We have seen that current trans- 

 forms the coil through which it flows 

 into a veritable magnet, with a N pole at 



FIG. 71. -The coil ro- One face and a S P le at the PP<>site 



tates between the face. The direction in which the cur- 



poles ol the magnet. -i j . i 



rent enters the coil determines which 

 face of the coil shall be the N pole and which the S 

 pole. ("General Science," page 335.) 



