Draw a ray diagram to show why a stick half immersed in water appears to be bent at the surface.

Suggest a reason for each of the following:

i. The sky near the horizon appears to have a reddish colour at the time of sunset and sunshine.

ii. The sun is visible to us two minutes before the actual sunrise and two minutes after the sunset.

An object is placed in front of a screen and a convex lens is placed at a position such that the size of the image formed is 9cm. when the lens is shifted through a distance of 20 cm, the size of the image becomes 1 cm. The focal length of the lens and the size of the object are respectively.

A thick plane-convex lens made of crown glass (refractive index 1.5) has thickness of 3 cm at its centre. The radius of curvature of the spherical surface is 5 cm.

An link mark made at the centre of its plane face, when viewed normal through the curved face, appears to be at a distance x from the curved face. Then, x is equal to

A convex lens A of focal length 20 cm and a concave lens B of focal length 5 cm are kept along the same axis with a distance d between them. If a parallel beam of light falling on A leaves B as a parallel beam, then the distance d in cm will be

The refractive index of a medium x with respect to y is 2/3 and the refractive index of medium y with respect to z is 4/3 Calculate the refractive index of medium z with respect to medium x

State the laws of refraction of light. Write an expression to relate absolute refractive index of a medium with speed of light in vacuum.