Ray Optics Test

Result

Ray Optics Test - 97

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
4 / -1

Two lamps of luminous intensity of 8 Cd and 32 Cd respectively are lying at a distance of 1.2 m from each other. Where should a screen be placed between two lamps such that its two faces are equally illuminated due to two sources

A
10 cm from 8 Cd lamp

B
10 cm from 32 Cd lamp

C
40 cm from 8 Cd lamp

D
40 cm from 32 Cd lamp

Solution
Question 2
4 / -1

A lamp is hanging along the axis of a circular table of radius r. At what height should the lamp be placed above the table, so that the illuminance at the edge ofthe table is 1/8 of that at its center

A

B

C

D

Solution
Question 3
4 / -1

Find the luminous intensity of the sun if it produces the same illuminance on the earth as produced by a bulb of 10000 candela at a distance 0.3 m. The distance between the sun and the earth is 1.5 × 10¹¹ m

A
25 × 10²² cd

B
25 × 10¹⁸ cd

C
25 × 10²⁶ cd

D
25 × 10³⁶ cd

Solution
Question 4
4 / -1

A lamp is hanging at a height 40 cm from the centre of a table. If its height is increased by 10 cm the illuminance on the table will decrease by

A
10%

B
20%

C
27%

D
36%

Solution
Question 5
4 / -1

Which has more luminous efficiency?

A
A 40 W bulb

B
A 40 W fluorescent tube

C
Both have same

D
Cannot say
Question 6
4 / -1

An electric lamp is fixed at the ceiling of a circular tunnel as shown is figure. What is the ratio the intensities of light at base A and a point B on the wall

A
1 : 2

B

C

D

Solution
Question 7
4 / -1

The relative luminosity of wavelength 600 nm is 0.6. Find the radiant flux of 600 nm needed to produce the same brightness sensation as produced by 120 W of radiant flux at 555 nm

A
50 W

B
72 W

C
120 × (0.6)² W

D
200 W

Solution
Question 8
4 / -1

Figure shows a glowing mercury tube. The illuminances at point A, B and C are related as

A
B > C > A

B
A > C > B

C
B = C > A

D
B = C < A
Question 9
4 / -1

A screen receives 3 watt of radiant flux of wavelength 6000 Å. One lumen is equivalent to 1.5 × 10^–3watt of monochromatic light of wavelength 5550 Å. If relative luminosity for 6000 Å is 0.685 while that for 5550 Å is 1.00, then the luminous flux of the source is

A
4 × 10³ lm

B
3 × 10³1m

C
2 × 10³ lm

D
1.37 × 10³ lm

Solution
Question 10
4 / -1

A point source of 3000 lumen is located at the centre of a cube of side length 2m. The flux through one side is

A
500 lumen

B
600 lumen

C
750 lumen

D
1500 lumen

Solution