Ray Optics and Optical Instruments · Question 31

In a microscope the objective is having focal length fo = 2 cm and eye-piece is having focal length fe = 4 cm. The tube length is 32 cm. The magnification produced by this microscope for normal adjustment is .

A collimated beam of light of diameter 2 mm is propagating along x-axis. The beam is required to be expanded in a collimated beam of diameter 14 mm using a system of two convex lenses. If first lens has focal length 40 mm, then the focal length of second lens is mm.

As shown in the diagram, when the incident ray is parallel to base of the prism, the emergent ray grazes along the second surface. [figure] If refractive index of the material of prism is 2, the angle of prism is.

1. 75
2. 90
3. 60
4. 45

A convex lens of focal length 30 cm is placed in contact with a concave lens of focal length 20 cm. An object is placed at 20 cm to the left of this lens system. The distance of the image from the lens in cm is .

1. 607
2. 15
3. 45
4. 30

A concave-convex lens of refractive index 1.5 and the radii of curvature of its surfaces are 30 cm and 20 cm, respectively. The concave surface is upwards and is filled with a liquid of refractive index 1.3. The focal length of the liquid-glass combination will be

1. 70011 cm
2. 60011 cm
3. 80011 cm
4. 50011 cm

Two thin convex lenses of focal lengths 30 cm and 10 cm are placed coaxially, 10 cm apart. The power of this combination is:

1. 5 D
2. 1 D
3. 20 D
4. 10 D

A lens having refractive index 1.6 has focal length of 12 cm, when it is in air. Find the focal length of the lens when it is placed in water. (Take refractive index of water as 1.28)

1. 355 mm
2. 655 mm
3. 288 mm
4. 555 mm

A container contains a liquid with refractive index of 1.2 up to a height of 60 cm and another liquid having refractive index 1.6 is added to height H above first liquid. If viewed from above, the apparent shift in the position of bottom of container is 40 cm. The value of H is cm. (Consider liquids are immiscible)

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). In the light of the above statements, choose the most appropriate answer from the options given below:

1. Both (A) and (R) are correct and (R) is the correct explanation of (A)
2. (A) is correct but (R) is not correct
3. (A) is not correct but (R) is correct
4. Both (A) and (R) are correct but (R) is not the correct explanation of (A)

A mirror is used to produce an image with magnification of 14. If the distance between object and its image is 40 cm, then the focal length of the mirror is .

1. 10 cm
2. 12.7 cm
3. 10.7 cm
4. 15 cm