Ray Optics and Optical Instruments · Question 78

In a concave lens, a ray of light emanating from the object parallel to the principal axis of the lens, after refraction :

1. passes through the second principal focus.
2. appears to diverge from the first principal focus.
3. passes through 2F, which is the radius of curvature of the lens.
4. emerges parallel to the principal axis.

A ray of monochromatic light is passing through an equilateral prism (ABC) as shown in the figure. The refracted ray (QR) is parallel to its base (BC) and the angle of incidence (i) is 50°. Then the angle of deviation (δ) is : [figure]

1. 45°
2. 55°
3. 35°
4. 40°

Consider three media P, Q and R with refractive indices 1, 1.25, and 1.5 respectively. The medium Q having a thickness of 5 cm is placed between extended media P and R as shown in the figure. An object O is placed at the centre of medium Q. If viewed from medium P near the normal direction, the apparent depth of O is h1. For similar observation from medium R, the apparent depth is h2. The value of |h1 - h2|, in cm, is: [figure]

1. 3
2. 0
3. 1
4. 2

The lens combination as shown in the figure, consists of two lenses, L1 and L2, of the focal lengths +10 cm and -10 cm, respectively. The position of the image formed is: [figure]

1. 60 cm to the right of the concave lens
2. 20 cm to the left of the concave lens
3. 60 cm to the left of the concave lens
4. 30 cm to the right of the concave lens

A microscope has an objective of focal length 2 cm, eyepiece of focal length 4 cm and the tube length of 40 cm. If the distance of distinct vision of eye is 25 cm, the magnification in the microscope is

1. 150
2. 250
3. 100
4. 125

In a certain camera, a combination of four similar thin convex lenses are arranged axially in contact. Then the power of the combination and the total magnification in comparison to the power (p) and magnification (m) for each lens will be, respectively

1. 4p and m4
2. p4 and m4
3. 4p and 4m
4. p4 and 4m

A light ray enters through a right angled prism at point P with the angle of incidence 30 as shown in figure. It travels through the prism parallel to its base BC and emerges along the face AC. The refractive index of the prism is: [figure]

1. 54
2. 52
3. 34
4. 32

A small telescope has an objective of focal length 140 cm and an eye piece of focal length 5.0 cm. The magnifying power of telescope for viewing a distant object is:

1. 34
2. 28
3. 17
4. 32

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

1. Statement I is correct but statement II is incorrect
2. Statement I is incorrect but Statement II is correct
3. Both Statement I and Statement II are correct
4. Both Statement I and Statement II are incorrect

Light travels a distance x in time t1 in air and 10x in time t2 in another denser medium. What is the critical angle for this medium?

1. -1 ( 10t2t1 )
2. -1 ( t110t2 )
3. -1 ( 10t1t2 )
4. -1 ( t2t1 )