398 



RAINBOW. BUBBLES. 



Here also the least refracted ray is BED, and the most 

 refracted BLUE (as in the former case) ; but the 

 position_of 'each is reversed. 



Q. Why does a SOAP BUBBLE exhibit such 



VARIETY Of COLOURS ? 



A. The changing colour of the bubble 

 depends upon the changing thickness of 

 the film through which the ray passes. 



Q. How does the THICKNESS of the FILM affect 

 the COLOUR of the soap bubble ? 



A. Because different degrees of thick- 

 ness produce different angles of refraction, 

 and, therefore, different colours reach the 

 eye. 



Q. Why is the SOAP BUBBLE so constantly 



CHANGING its THICKNESS ? 



