Question

Violet light is incident on a thin convex lens. If this light is replaced by red light , explain with reason, how the power of the lens would change ?

Answer 1

Power of lens$P=\frac{1}{f}=(n-1)(\frac{1}{R_1}-\frac{1}{R_2})$

Refractive index of lens for violet rays is more than that for red rays, so power of a lens will decrease if violet light is replaced by red light.