Question

How does the power of a lens change if red colour light is replaced by the violet light

Answer 1

Focal length of a lens varies linearly with wavelength of light used. This is what leads to chromatic dispersion! Since violet light has a shorter wavelength compared to red light, focal length of a lens will decrease if red light is replaced by violet light.

Answer 2

Answer:

powerof the convex lens increases with the increase in wavelength. We know wavelength of red is more than the wavelength of violet. So, as the wavelength decreases the focal length also decreases.