Question

How to find focal length of convex lens using auxillary convex lens

Answer 1

An optical bench with four upright (two fixed uprights in middle, two outer uprights with lateral movement), a convex lens (less focal length), a concave lens (more focal length), two lens holders, two optical needles (one thin, one thick), a knitting needle and a half metre scale.

Answer 2

Answer:

The focal length of a convex lens increases as the wavelength increases. This is so because the refractive index decreases with an increase in wavelength of light.