Light Test

Result

Light Test - 1

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Weekly Quiz Competition

Question 1
1 / -0

Read the following statements and choose the correct option accordingly:

Statement A: Reflection from the water surface is diffused reflection.
Statement B: In diffused reflection, a parallel beam, after reflection, does not remain parallel.

A
Both the statements are correct.

B
Statement A is correct, but statement B is incorrect.

C
Statement A is incorrect, but statement B is correct.

D
Both the statements are incorrect.

Solution

Statement A is incorrect, but statement B is correct.

Reflection from the water surface is specular reflection as water surface acts as a plane surface.

In diffused reflection, if parallel rays strike a rough surface, then the reflected rays will not be parallel. Hence, it will produce a diffused image.
Question 2
1 / -0

A beam of light is incident at an angle of 30° on a plane mirror. The mirror is then rotated by an angle of 20°.

By what angle will the reflected beam rotate?

A
20°

B
30°

C
40°

D
50°

Solution

If the mirror is rotated by an angle θ, the reflected ray will be rotated by an angle 2θ in the sense of rotation of mirror.

If the mirror is rotated clockwise, the reflected ray will be rotated clockwise and vice versa.

Hence, the answer is 40°.
Question 3
1 / -0

An object is moving towards a plane mirror with a velocity of 2 m/s. At what speed does the image approach the object?

A
4 m/s

B
2 m/s

C
1 m/s

D
0.5 m/s

Solution

Velocity of image with respect to mirror = 2 m/s

As the observer moves towards the mirror, the image moves closer to the mirror with same speed, but in opposite direction. Hence, their relative velocity adds up.

So, the image approaches the object with a speed of 4 m/s.
Question 4
1 / -0

Read the following statements and choose the correct option accordingly:

Statement A: Refractive index determines the optical density of a medium.
Statement B: Refractive index is independent of the wavelength of the light.

A
Both statements A and B are correct.

B
Statement A is correct, but statement B is incorrect.

C
Statement A is incorrect, but statement B is correct.

D
Both statements A and B are incorrect.

Solution

Refractive index is the physical property which determines the optical density of a material. Greater the refractive index of a medium, lesser is the speed of light in that medium. So, statement A is correct.

Refractive index of a medium is inversely proportional to the wavelength of light. Greater the wavelength of light, lesser is the refractive index of the medium. So, statement B is incorrect.
Question 5
1 / -0

Read the following statements and choose the correct option accordingly.

Statement A: During the propagation of light from a denser medium to a rarer medium, light bends away from the normal.
Statement B: During refraction, there is no change in the frequency of light.

A
Both statements A and B are correct.

B
Statement A is correct, but statement B is incorrect.

C
Statement A is incorrect, but statement B is correct.

D
Both statements A and B are incorrect.

Solution

Whenever the light travels from a denser medium to a rarer medium, it always bends away from the normal. So, statement A is correct.

During the propagation of light from one medium into another medium, there is no change in the frequency of the light, but speed and wavelength of the light do change. So, statement B is also correct.