Question

By increasing the aperture of the objective lens, wavelength of light, focal length of the objective lens and the resolving power of an astronomical telescope respectively.

Options

• is not affected, increases, increases

• decreases, increases, is not affected

• increases, decreases, is not affected

• is not affected, increases, decreases

Answer 1

Is not affected, increases, increases

Explanation:

The resolving power of astronomical telescope,

R = `1/(Delta "x") = (2mu sin theta)/lambda = "NA"/lambda`

where, NA = numerical aperture of objective lens.

On increasing the aperture, the value of R increases.

On increasing the aperture of the objective lens medium remains same, hence wavelength of light is not affected on increasing the aperture of objective lens its focal length Increases.