Ray Optics and Optical Instruments

Light from a point source in air falls on a convex curved surface of radius 20 cm and refractive index 1.5. If the source is located at 100 cm from the convex surface, the image will be formed at cm from the object.

The distance between object and its two times magnified real image as produced by a convex lens is 45 cm. The focal length of the lens used is cm.

In an experiment to measure the focal length (f) of a convex lens, the magnitude of object distance (x) and the image distance (y) are measured with reference to the focal point of the lens. The y-x plot is shown in figure. The focal length of the lens is cm. [figure]

A convex mirror of radius of curvature 30 cm forms an image that is half the size of the object. The object distance is :

1. -45 cm
2. -15 cm
3. 45 cm
4. 15 cm

A biconvex lens of refractive index 1.5 has a focal length of 20 cm in air. Its focal length when immersed in a liquid of refractive index 1.6 will be:

1. -16 cm
2. +16 cm
3. +160 cm
4. -160 cm

If the distance between object and its two times magnified virtual image produced by a curved mirror is 15 cm, the focal length of the mirror must be:

1. -10 cm
2. -12 cm
3. 15 cm
4. 10/3 cm

If the refractive index of the material of a prism is ( A2 ), where A is the angle of prism then the angle of minimum deviation will be

1. - 2A
2. 2-2A
3. - A
4. 2-A

Two immiscible liquids of refractive indices 85 and 32 respectively are put in a beaker as shown in the figure. The height of each column is 6 cm. A coin is placed at the bottom of the beaker. For near normal vision, the apparent depth of the coin is 4 cm. The value of is . [figure]