question_answer

A soap bubble has a thickness of 100 nm and a refractive index of 1.35. Given that the wavelength of red light is about 700 nm and that of blue light is 400 nm, what colour does the bubble appear to be at the point on its surface closest to an observer when it is illuminated by white light?

A)  White  

B)  Black

C)  Red                 

D)  Green