The wave lengths for the light of red and blue colours

Light (10)

The wave lengths for the light of red and blue colours are nearly 7.8 x 10-7 m and 4.8x 10-7 m respectively.

  1. Which colour has the greater speed in a vacuum?
  2. Which colour has a greater speed in glass?

Answer

(i) In vacuum, both have the same speed.

(ii) In glass, red light has greater speed.