Ray Optics and Optical Instruments

In the diagram given below, there are three lenses formed. Considering negligible thickness of each of them as compared to |R1| and |R2|, i.e., the radii of curvature for upper and lower surfaces of the glass lens, the power of the combination is [figure]

1. - 16 ( 1|R1|- 1|R2| )
2. - 16 ( 1|R1|+ 1|R2| )
3. 16 ( 1|R1|+ 1|R2| )
4. 16 ( 1|R1|- 1|R2| )

Given is a thin convex lens of glass (refractive index ) and each side having radius of curvature R. One side is polished for complete reflection. At what distance from the lens, an object be placed on the optic axis so that the image gets formed on the object itself?

1. R/
2. R/(2 -1)
3. R/(2 -3)

A symmetric thin biconvex lens is cut into four equal parts by two planes AB and CD as shown in figure. If the power of original lens is 4D then the power of a part of the divided lens is [figure]

1. 2D
2. 8D
3. 4D
4. D

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

1. Statement I is false but Statement II is true
2. Both Statement I and Statement II are false
3. Both Statement I and Statement II are true
4. Statement I is true but Statement II is false

The following figure represents two biconvex lenses L1 and L2 having focal length 10 cm and 15 cm respectively. The distance between L1 & L2 is : [figure]

1. 25 cm
2. 35 cm
3. 10 cm
4. 15 cm

Critical angle of incidence for a pair of optical media is 45 . The refractive indices of first and second media are in the ratio:

1. 1 : 2
2. 1 : 2
3. 2 : 1
4. 2 : 1

The position of the image formed by the combination of lenses is : [figure]

1. 15 cm (right of second lens)
2. 30 cm (right of third lens)
3. 30 cm (left of third lens)
4. 15 cm (left of second lens)

For the thin convex lens, the radii of curvature are at 15 cm and 30 cm respectively. The focal length of the lens is 20 cm. The refractive index of the material is :

1. 1.2
2. 1.5
3. 1.4
4. 1.8

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

1. Both Statement I and Statement II are true
2. Statement I is true but Statement II is false
3. Statement I is false but Statement II is true
4. Both Statement I and Statement II are false

An effective power of a combination of 5 identical convex lenses which are kept in contact along the principal axis is 25D. Focal length of each of the convex lens is:

1. 50 cm
2. 20 cm
3. 25 cm
4. 500 cm

The refractive index of a prism with apex angle A is A/2. The angle of minimum deviation is :

1. m=180 -3A
2. m=180 -4A
3. m=180 -2A
4. m=180 -A

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