Ray Optics Test

Result

Ray Optics Test - 94

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Weekly Quiz Competition

Question 1
4 / -1

The sun\'s diameter is 1.4 × 10⁹m and its distance fromthe earth is 10¹¹ nm. The diameter of its image, formed by a convex lens of focal length 2 m will be

A
0.7 cm

B
1.4 cm

C
2.8 cm

D
Zero (i.e., point image)

Solution
Question 2
4 / -1

The focal lengths of the objective and of the eye-piece of a compound microscope are f₀ and f_e respectively. If L is the tube length and D, the least distance of distinct vision, then its angular magnification, when the image is formed at infinity, is

A

B

C

D
Question 3
4 / -1

The length of a telescope is 36 cm. The focal lengths of its lenses can be

A
30 cm, 6 cm

B
– 30 cm, – 6 cm

C
30 cm, – 6 cm

D
– 30 cm, 6 cm

Solution
Question 4
4 / -1

An astronomical telescope of ten-fold angular magnification has a length of 44 cm. The focal length of the objective is

A
4 cm

B
40 cm

C
44 cm

D
440 cm

Solution
Question 5
4 / -1

If both the object and image are at infinite distance from a refracting telescope its magnifying power will be equal to

A
The sum of the focal lengths of the objective and the eyepiece

B
The difference of the focal lengths of the two lenses

C
The ratio of the focal length of the objective and eyepiece

D
The ratio of the focal length of the eyepiece and objective

Solution
Question 6
4 / -1

The number of lenses in a terrestrial telescope is

A
Two

B
Three

C
Four

D
Six

Solution
Question 7
4 / -1

The focal lengths of the lenses of an astronomical telescope are 50 cm and 5 cm. The length of the telescope when the image is formed at the leastdistance of distinct vision is

A
45 cm

B
55 cm

C

D

Solution
Question 8
4 / -1

If luminous efficiency of a lamp is 2 lumen/watt and its luminous intensity is 42 candela, then power of the lamp is

A
62 W

B
76 W

C
138 W

D
264 W

Solution
Question 9
4 / -1

An electric bulb illuminates a plane surface. The intensity of illumination on the surface at a point 2m away from the bulb is 5 × 10^–4 phot (lumen/cm²). Theline joining the bulb to the point makes an angle of 60° with the normal to the surface. The intensity of the bulb in candela is

A
40√3

B
40

C
20

D
40 × 10^–4

Solution
Question 10
4 / -1

In a movie hall, the distance between the projector and the screen is increased by 1% illumination on the screen is

A
Increased by 1%

B
Decreased by 1%

C
Increased by 2%

D
Decreased by 2%

Solution