Question

For a simple converging lens with a higher index of refraction for blue light than for red light, is the focal length longer for red light or longer for blue light? Maximum number of characters (including HTML tags added by text editor): 32,000 Show Rich-Text Editor (and character count)

Answer 1

Focal length is longer for red light.This is so because due to less index of refraction it bends less than blue light. So it crosses principle axis ahead of blue light's crossing point on principle axis.