Ray Optics Test

Result

Ray Optics Test - 104

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Weekly Quiz Competition

Question 1
4 / -1

A compound microscope is used to enlarge an object kept at a distance 0.03m from it\'s objective which consists of several convex lenses in contact and has focal length 0.02m. If a lens of focal length 0.1m is removed from the objective, then by what distance the eye-piece of the microscope must be moved to refocus the image

A
2.5 cm

B
6 cm

C
15 cm

D
9 cm

Solution
Question 2
4 / -1

If the focal length of the objective lens and the eye lens are 4 mm and 25 mm respectively in a compound microscope. The length of the tube is 16 cm. Find its magnifying power for relaxed eye position

A
32.75

B
327.5

C
0.3275

D
None of these

Solution
Question 3
4 / -1

Three right angled prisms of refractive indices n₁, n₂ and n₃ are fixed together using an optical glue as shown in figure. If a ray passes through the prisms without suffering any deviation, then

A
n₁ = n₂ = n₃

B
n₁ = n₂ ≠ n₃

C
1 + n₁ = n₂ + n₃

D

Solution
Question 4
4 / -1

In a compound microscope, the focal length of the objective and the eye lens are 2.5 cm and 5 cm respectively. An object is placed at 3.75 cm before the objective and image is formed at the least distance of distinct vision, then the distance between two lenses will be (i.e., length of the microscopic tube)

A
11.67 cm

B
12.67 cm

C
13.00 cm

D
12.00 cm

Solution
Question 5
4 / -1

In a grease spot photometer light from a lamp with dirty chimney is exactly balanced by a point source distance 10 cm from the grease spot. On clearing the chimney, the point source is moved 2 cm to obtain balance again. The percentage of light absorbed by dirty chimney is nearly

A
56%

B
44%

C
36%

D
64%

Solution
Question 6
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 7
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 8
4 / -1

A point object is placed at a distance of 20 cm from a thin plano-convex lens of focal length 15 cm , if the plane surface is silvered. The image will form at

A
60 cm left of AB

B
30 cm left of AB

C
12 cm left of AB

D
60 cm right of AB

Solution
Question 9
4 / -1

A bi-convex lens of focal length f forms a circular image of sun of radius r in focal plane. Then

A

B

C

D
If f is doubled, intensity will increase

Solution
Question 10
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