Physics · Science General

Optics and Light Properties

2,019 Questions

Optics and light properties focus on the behavior of light, including reflection, refraction, dispersion, and polarization. This topic also covers the wave nature of light, illumination, and the functioning of optical instruments like microscopes. Questions on these concepts are common in general science sections of SSC, Railways, and State exams.

Reflection and mirrorsRefraction and mediumsLight wave theoriesPolarization and intensity

Optics and Light Properties Questions

Multiple choice

A bubble of water shines because of

  1. reflection

  2. refraction

  3. total internal reflection

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A bubble of water shines because of total internal reflection.

Multiple choice

The speed of light will be minimum while passing through

  1. glass

  2. air

  3. water

  4. vacuum
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The speed of light is highest in a vacuum and slows down as the refractive index of the medium increases. Glass has the highest refractive index among the options, so light travels slowest through it.

Multiple choice

Match the following:

 
Parameters
Dependence
A. Intensity of light

B. Color of light C. Velocity of light D. Propagation of light | 1. Properties of the medium 2. Refractive index of the medium 3. Amplitude of light 4. Frequency of light |

  1. A - 2, B - 4, C - 1, D - 3

  2. A - 3, B - 4, C - 2, D - 1

  3. A - 3, B - 1, C - 2, D - 4

  4. A - 4, B - 2, C - 3, D - 1
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Intensity depends on amplitude (A-3). Color depends on frequency (B-4). Velocity depends on the medium's refractive index (C-2). Propagation depends on the properties of the medium (D-1).

Multiple choice

Lambert's law is related to

  1. Reflection

  2. Refraction

  3. Interference

  4. Illumination
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Lambert's Cosine Law relates to the intensity of light reflected or emitted from a surface, making it a law of illumination.

Multiple choice

Although fog consists of fine drops of water, we cannot see clearly through it because

  1. the light rays undergo total internal reflection in the drops

  2. fine drops of water in fog polarize the light

  3. the fine drops are opaque to the light

  4. the drops scatter most of the light
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Fog consists of tiny water droplets suspended in the air. These droplets are large enough to scatter light, which prevents clear vision through the fog.

Multiple choice

Assertion: When white light falls on a substance, it absorbs a particular colour in the visible region. Reason: The colour of the absorbed light is the colour of the substance.

Directions: In each of the questions given below, there are two statements labeled as Assertion (A) and Reason (R). Mark your answer as per the codes provided below:

A. Both A and R are true and R is the correct explanation of A.
B. Both A and R are true but R is not the correct explanation of A.
C. A is true but R is false.
D. A is false but R is true.
E. Both A and R are false.

  1. Both A and R are true and R is the correct explanation of A.

  2. Both A and R are true but R is not the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.

  5. Both A and R are false.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This option is correct because when white light falls on a substance, it absorbs a particular colour in the visible region (4000-7000 Ǻ) and reflects the remaining light which has the colour complementary to that of the absorbed light. The colour of the reflected light is the colour of the substance.

Multiple choice

Why does the sky look blue?

  1. Sky is actually blue in colour.

  2. Sky is the reflection of sea water that is why it is blue.

  3. Blue colour of light is of short wave length so can be scattered by dust particles and water vapours but not the other colours.

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Rayleigh scattering explains that shorter wavelengths of light (blue and violet) are scattered more efficiently by the atmosphere's molecules and particles than longer wavelengths (red). This scattered blue light reaches our eyes from all directions in the sky.

Multiple choice

Optimum growth occurs in

  1. blue light

  2. red light

  3. white light

  4. green light
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

White light contains the full spectrum of wavelengths necessary for photosynthesis and optimal plant growth.

Multiple choice

Lambert (Lb) is a unit for

  1. Luminance in MKS

  2. Luminance in FPS

  3. Luminance in CGS

  4. Luminance in SI
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

3   Luminance is the luminous intensity of a surface, measuring the intensity of the light emitted (or reflected) in all directions per unit of area of the surface. One Lambert is the luminance of a surface that emits or reflects one lumen per square centimetre.

Multiple choice

The light waves are-

  1. Electric waves

  2. Magnetic waves

  3. Electromagnetic waves

  4. Electrostatic waves
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Light waves consist of oscillating electric and magnetic fields that are perpendicular to each other and to the direction of wave propagation, hence they are electromagnetic waves.

Multiple choice

How many times does light reflects in a periscope?

  1. 1

  2. 2

  3. 3

  4. 4
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A standard periscope uses two plane mirrors placed at 45-degree angles to each other. Light reflects off the first mirror and then the second mirror to reach the observer's eye.