LIGHT WAVES 



Light consists of waves transmitted through the ether. Waves of light differ in length. The colour of the 

 light depends on the wave-length. Deep-red waves (the longest) are 2 ^ ssa inch and deep-violet waves 

 IT! inch. The diagram shows two wave-motions of different wave-lengths. From crest to crest, or from 

 trough to trough, is the length of the wave. 





THE MAGNETIC CIRCUIT OF AN ELECTRIC CURRENT 



The electric current passing in the direction of the arrow round the electric 

 circuit generates in the surrounding space circular magnetic circuits as shown in 

 the diagram. It is this property which lies at the base of the electro-magnet and 

 of the electric dynamo. 



THE MAGNET 



The illustration shows the lines of force between two magnets. The lines of 



ce proceed from the north pole of one magnet to the south pole of the other. 



hey also proceed from the north to the south poles of the same magnet. 



The.e facts are shown clearly in the diagram. The north pole of a magnet is 



it which turns to the north when the magnet is freely suspended. 



