38 



FIRST YEAR SCIENCE 



nickel and cobalt and a few other substances have a little at- 

 traction. Thus steel and iron are always used for magnets. 



Experiment 14. Wind 

 twenty feet of No. 20 in- 

 sulated copper wire around 

 the nail used in Experiment 

 13 as you would wind thread 

 on a spool. Attach one end 

 of this wire to each pole of 

 a dry cell. Bring the nail 

 thus arranged toward a sus- 

 pended magnet. Reverse 

 act as it did before it was 



Fig. 14. 



the ends of the nail. Does the nail 

 placed within the coil of wire 

 connected to the battery? 

 Bring another nail in con- 

 tact with its ends. What 

 happens? What, has the 

 nail as arranged become? 

 Disconnect one of the wires 

 from the battery and try the 

 test again. Does the nail 

 act as it did when the bat- 

 tery was connected ? 



We found that if a 

 nail is placed in a coil 

 of wire connected with 

 an electric battery it 

 becomes magnetic, but 

 only as long as the con- 

 nection is maintained. 

 Magnets of this kind 

 are called electromagnets. 

 If the nail had been hard 



MAGNETIC CRANE. 



The electromagnet is lifting tons of scrap 

 iron. 



steel and the battery exceedingly strong, the steel would 

 have remained a magnet after being taken out of the coil. 



