A biconvex lens has radii of curvature, 20 cm each. If the refractive index of the material of the lens is 1.5, the power of the lens is
In a Young's double slit experiment, a student observes 8 fringes in a certain segment of screen when a monochromatic light of 600 nm wavelength is used. If the wavelength of light is changed to 400 nm, then the number of fringes he would observe in the same region of the screen is
A light ray falls on a glass surface of refractive index $$\sqrt3$$, at an angle 60$$^\circ$$. The angle between the refracted and reflected rays would be
When light propagates through a material medium of relative permittivity $$\varepsilon $$r and relative permeability $$\mu$$r, the velocity of light, v is given by (c-velocity of light in vacuum)