A glass slab has refractive index '$$\mu$$' with respect to air and the critical angle for a ray of light in going from glass to glass to air is '$$\theta$$' If a ray of light is incident from air on the glass with angle of incidence '$$\theta$$', then the corresponding angle of refraction is
'Circle of least confusion' refers to which one of the following defects occurring in images formed by mirrors or lenses?
A plano-convex lens of refractive index ($$\mu_1^{\prime}$$ fits exactly into a plano-concave lens of refractive index $$\mu_2$$. Their plane surface are parallel to each other. 'R' is the radius of curvature of the curved surface of the lenses. The focal length of the combination is
The magnifying power of a refracting type of astronomical telescope is '$$\mathrm{m}$$'. If focal length of eyepiece is doubled then the magnifying power will become