Ray Optics and Optical Instruments

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]