BREAK EXTRA-CURRENT 15 



the tongue. Neither on opening nor closing the key k. 3 is any distinct shock 

 felt unless the battery is very strong. Now open the key k } and again open 

 and close k.,. Each time the key K 2 is opened the current is sent through the 

 tongue, and the resistance being very high there is a sudden fall in strength 

 of the current. On opening a distinct shock is felt. This is due to the 

 extra-current brought about by the sudden fall in strength, inducing currents 

 in the turns of wire of the primary coil p c. 



