A zone plate of focal length , 60cm behaves as a convex lens, If wavelength of incident light is , `6000 Å` then radius of first half period zone will be

How does focal length of a convex lens change with increase in wavelength of incident light?

The radius of nth half period zone is proportional to :

The radius r of half period zone is proportional to

Briefly explain,how the focal length of a convex lens changes with increase in wavelength of incident light.

Explain briefly how the focal length of a convex lens changes with increase in wavelength of incident light.

A diffraction pattern is produced by a single slit of width 0.5mm with the help of a convex lens of focal length 40cm. If the wavelength of light used is 5896Å. then the distance of first dark fringe from the axis will be-