To a diver inside water, the setting sun will appear at an angle (with the horizontal) of: \(\left[ \mu_w = \frac{5}{4} \right]\)

1.	\(53^{\circ}\)	2.	\(37^{\circ}\)
3.	\(45^{\circ}\)	4.	\(60^{\circ}\)

In normal adjustment, the angular magnification of an astronomical telescope is 39. If the length of the tube is 2 m, then the focal length of the objective and eyepiece are respectively,

(1) 195 cm, 5 cm

(2) 190 cm, 10 cm

(3) 20 cm, 180 cm

(4) 10 cm, 190 cm

The following diagram shows a glass sphere of radius 10 cm with a paraxial incident ray. The refractive index of the material of the glass is

1.  2

2.  1.5

3.  1.75

4.  1.3

A convex lens of focal length 10 cm form real image of an object. The distance between the object and the image may be:

(1) 25 cm

(2) 30 cm

(3) 38 cm

(4) 50 cm

Two plane mirrors are placed perpendicular to each other as shown in the figure. An object O is kept at the angular bisector of the two mirrors. Numbers of images of object O is formed, will be:

1.  4

2.  3

3.  2

4.  1

Two convex lenses of focal lengths 10 cm and 30 cm are kept at a separation of 20 cm. Then the correct statement is:

(1) The effective focal length is 15 cm

(2) Chromatic aberration is minimized

(3) Combination behaves like a convergent lens 

(4) All of these

If one surface of a biconvex lens is silvered, then it behaves as

(1) A concave mirror of focal length $\frac{R}{4\mu -2}$

(2) A concave mirror of focal length $\frac{R}{2\mu }$

(3) A convex mirror of focal length $\frac{R}{4\mu -2}$

(4) A concave mirror of focal length $\frac{R}{2\mu -2}$

An astronomical telescope has an angular magnification of 20 in its normal adjustment. The focal length of the eyepiece is 4 cm. Distance between objective and eyepiece is:

1.  80 cm

2. 84 cm

3.  76 cm

4.  90 cm