Ray Optics Test

Result

Ray Optics Test - 157

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Weekly Quiz Competition

Question 1
4 / -1

An object is placed infront of a convex mirror at a distance of 50 cm. A plane mirror is introduced covering the lower half of the convex mirror. If the distance between the object and plane mirror is 30 cm, it is found that there is no parallax between the images formed by two mirrors. Radius of curvature of mirror will be

A
12.5 cm

B
25 cm

C
50/3cm

D
18 cm

Solution
Question 2
4 / -1

A small piece of wire bent into an L shape with upright and horizontal portions of equal lengths, is placed with the horizontal portion along the axis of the concave mirror whose radius of curvature is 10 cm. If the bend is 20 cm from the pole of the mirror, then the ratio of the lengths of the images of the upright and horizontal portions of the wire is

A
1 : 2

B
1 : 3

C
3 : 1

D
2 : 1

Solution
Question 3
4 / -1

Two point light sources are 24 cm apart. Where should a convex lens of focal length 9 cm be put in between them from one source so that the images of both the sources are formed at the same place

A
6 cm

B
9 cm

C
12 cm

D
15 cm

Solution
Question 4
4 / -1

There is an equiconvex glass lens with radius of each face as R and _aµ_g = 3/2 and _aµ_w = 4/3. If there is water in object space and air in image space, then the focal length is

A
2R

B
R

C
3 R/2

D
R²

Solution
Question 5
4 / -1

The separation between the screen and a plane mirror is 2r. An isotropic point source of light is placed exactly midway between the mirror and the screen. Assume that mirror reflects 100% of incident light. Then the ratio of illuminances on the screen with and without the mirror is

A
10 : 1

B
2 : 1

C
10 : 9

D
9 : 1

Solution
Question 6
4 / -1

The separation between the screen and a concave mirror is 2r. An isotropic point source of light is placed exactly midway between the mirror and the screen. Mirror has a radius of curvature r and reflects 100% of the incident light. Then the ratio of illuminances on the screen with and without the mirror is

A
10 : 1

B
2 : 1

C
10 : 9

D
9 : 1

Solution
Question 7
4 / -1

The apparent depth of water in cylindrical water tank of diameter 2R cm is reducing at the rate of x cm/ minute when water is being drained out at a constant rate. The amount of water drained in c.c. per minute is (n₁ = refractive index of air, n₂ = refractive index of water)

A
xπR²n₁/n₂

B
xπR² n₂/n₁

C
2 πR n₁/n₂

D
πR²x

Solution
Question 8
4 / -1

The image of a small electric bulb fixed on the wall of a room is to be obtained on the opposite wall 4m away by means of a large convex lens. The maximum possible focal length of the lens required for this purpose will be

A
0.5 m

B
1.0 m

C
1.5 m

D
2.0 m

Solution
Question 9
4 / -1

A concave mirror of focal length ‘f₁\' is placed at a distance of ‘d₁\' from a convex lens of focal length ‘f₂\'. A beam of light coming from infinity and falling on this convex lens concave mirror combination returns to infinity. The distance \'d\' must equal

A
f₁ + f₂

B
–f₁ + f₂

C
2 f₁ + f₂

D
–2 f₁ + f₂

Solution
Question 10
4 / -1

In an experiment to find the focal length of a concave mirror a graph is drawn between the magnitudes of u and v. The graph looks like

A

B

C

D

Solution