1. If the focal length of objective lens is increased, then magnifying power of

(1).microscope will increase but that of telescope decrease

(2). microscope and telescope both will increase

(3). microscope and telescope both will decrease

(4). microscope will decrease but that of telescope increase

2. The angle of a prism is A. One of its refracting surfaces is silvered. Light rays falling at an angle of incidence 2A on the first surface returns back through the same path after suffering reflection at the silvered surface. The refractive index \(\mu\), of the prism is

(1).2 sin A

(2). 2 cos A

(3). 1/2 cos A

(4). tan A

3. A light ray enters through a right angled prism at point P with the angle of incidence \(30^ \circ\) 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 :

(1).\(\displaystyle \frac{\sqrt{3}}{4}\)

(2). \(\displaystyle \frac{\sqrt{3}}{2}\)

(3). \(\displaystyle \frac{\sqrt{5}}{4}\)

(4). \(\displaystyle \frac{\sqrt{5}}{2}\)

4. 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 ?

(1).17

(2). 32

(3). 34

(4). 28

5. A light ray falls on a glass surface of refractive index \(\sqrt{3}\) , at an angle \(60^ \circ\) . The angle between the refracted and reflected rays would be :

(1).\(30^\circ\)

(2). \(60^\circ\)

(3). \(90^\circ\)

(4). \(120^\circ\)

6. The transparent media A and B are separated by a plane boundary. The speed of light in those media are \(1.5 \times 10^ 8 \,m/s\) and \(2.0 \times 10^8 \,m/s\), respectively. The critical angle for a ray of light for these two media is :

(1).\(sin^{–1}\left(0.500\right)\)

(2). \(sin^{–1}\left(0.750\right)\)

(3). \(tan^{–1}\left (0.500\right)\)

(4). \(tan^{ –1}\left (0.750\right)\)

7. A ray is incident at an angle of incidence i on one surface of a small angle prism (with angle of prism A) and emerges normally from the opposite surface. If the refractive index of the material of the prism is \(\mu\), then the angle of incidence is nearly equal to

(1).\(\displaystyle \frac{2\, \text{A}}{\mu}\)

(2). \(\mu \text{A}\)

(3). \(\displaystyle \frac{\mu \, \text{A}}{2}\)

(4). \(\displaystyle \frac{\text{A}}{2\,\mu}\)

8. Two identical thin plano – convex glass lenses (refractive index 1.5) each having radius of curvature of 20 cm are placed with their convex surface in contact at the centre. The intervening space is filled with oil of refractive index 1.7. The focal length of the combination is:

(1).- 20 cm

(2). - 20 cm

(3). - 50 cm

(4). 50 cm

9. The refracting angle of a prism is A, and refractive index of the material of the prism is cot(A/2). The angle of minimum deviation is:

(1).180° - 3A

(2). 180° - 2A

(3). 90° - A

(4). 180° 2A

10. In a certain camera, a combination of four 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).\(\text{p}^4\) and \(\text{m}^4\)

(2). \(4\text{p}\) and \(4\text{m}\)

(3). \(\text{p}^4\) and \(4\text{m}\)

(4). \(4\text{p}\) and \(\text{m}^4\)

11. 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 microscope is

(1).250

(2). 100

(3). 125

(4). 150