Ray Optics Test

Result

Ray Optics Test - 27

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Weekly Quiz Competition

Question 1
4 / -1

Dispersive power depends on the following

A
material of the prism

B
shape of the prism

C
size of the prism

D
size, shape and material of the prism
Question 2
4 / -1

Two thin lenses of focal lengths f₁ and f₂ are placed in contact with each other. The focal length of the combination is

A

B

C

D
Question 3
4 / -1

A convex lens is in contact with concave lens. The magnitude of the ratio of their focal length is 2/3. Their equivalent focal length is 30 cm. What are their individual focal lengths?

A
– 75, 50

B
–10, 15

C
75, 50

D
–15, 10
Question 4
4 / -1

A thin glass (refractive index 1.5) lens has optical power of - 5 D in air. Its optical power in a liquid medium with refractive index 1.6 will be

A
1 D

B
– 1D

C
25 D

D
– 25 D

Solution
Question 5
4 / -1

Refractive index of glass with respect to medium is 4/3. If the differences between velocities of light in medium and glass is 6.25 × 10⁷ ms^-1, then velocity of light in medium is

A
2.5 × 10⁸ ms^-1

B
0.125 × 10⁸ ms^-1

C
1.5 × 10⁸ ms^-1

D
3 × 10⁸ ms^-1

Solution
Question 6
4 / -1

The focal length of an equi-convex lens is greater than the radius of curvature of any of the surfaces. Then, the refractive index of the material of the lens is

A
greater than zero but less than 1.5

B
greater than 1.5 but less than 2.0

C
greater than 2.0 but less than 2.5

D
greater than 2.5 but less than 2.0
Question 7
4 / -1

An electric bulb of luminous intensity I is suspended at a height h from centre of the table having a circular surface diameter 2 r. The illuminance at centre of circular dis will be

A
I/r²

B
I/r

C
I/h²

D
I/h

Solution
Question 8
4 / -1

At what distance should a book be placed from a 50 Cd bulb so that the illuminance on the book becomes 2 lmm^–2 ?

A
1 m

B
5 m

C
10 m

D
50 m

Solution
Question 9
4 / -1

A point source of 100 candela is held 5m above a sheet of blotting paper which reflects 75% of light incident upon it. The illuminance of blotting paper is

A
4 phot

B
4 lux

C
3 phot

D
3 lux

Solution
Question 10
4 / -1

Luminous flux and luminous intensity are related as

A

B

C

D