Physics Ray Optics and Optical Instruments

If a biconvex lens of material of refractive index 1.5 has focal length 20 cm in air, then its focal length when it is submerged in a medium of refractive index 1.6 is

Distance between virtual image, which is of twice of size of object placed in front of mirror and object is 45 cm. Magnitude of focal length of mirror is _______ cm.

Radius of curvature of equiconvex lens is 20 cm. Material of lens is having refractive index of 1.5. Find image distance from lens if an object is placed 10 cm away from the lens.

A farsighted person cannot focus distinctly objects closer than 100 cm. The lens that will permit him to read from a distance of 50 cm, will have a focal length:

A prism has refracting angle of 30⁰ and it is made of glass of refractive index $\sqrt[]{2}$ . At what angle should a light ray be incident on a face of prism such that it passes normally through the other face?

A telescope with objective of focal length $100cm$ and eyepiece of focal length $5cm$ is focused on a far object such that parallel rays emerge from eyepiece. If object subtends an angle of $1^0$ on objective, the angular size of image is

Deviation of light ray by a thin prism of refractive index $\mu$ and refracting angle $A$  is

A small coin is resting on the bottom of a beaker filled with liquid. A ray of light from the coin travels upto the surface of the liquid and moves along its surface. How fast is the light travelling in the liquid?

An object of height 1.5cm is placed on the axis of a convex lens of focal length 25cm. A real image is formed at a distance of 75cm from the lens. The size of the image will be

A circular beam of light of diameter d=2cm falls on a plane surface of glass. The angle of incidence is 60⁰ and refractive index of glass is $\mu =3/2$ . The diameter of the refracted beam is: