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

On which of the following factors does the shape of a shadow depend?

  1. Shape and size of the source of light

  2. Size and position of the source of light

  3. Shape and distance of the source of light

  4. Direction and shape of the source of light
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A shadow is always formed by an opaque object. The shape of a shadow depends upon two factors:

  1. Size of the source of light
  2. Position of the source of light. Smaller the size of the light source, larger will be the image formed and greater is the distance between the object and the light source, lighter will be the image formed.
Multiple choice

Which type of objects block the path of light?

  1. Opaque

  2. Translucent

  3. Luminous

  4. Transparent
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Transparent objects
Allow light to pass through and can clearly see through them
Water, air, glass, cellophane, plastic sheet
Translucent objects
Allow light to pass through partially and cannot see clearly through them
Frosted glass, plastic ruler, butter paper
Opaque objects
Do not allow light to pass through and cannot see through them
Table, chair, book, iron (or any metal)

So, opaque objects block the path of the light.

Multiple choice

Which of the following phenomena can change the direction of the light?

  1. Conduction

  2. Insulation

  3. Reflection

  4. Transparency

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Light rays always travel in straight lines. When a light ray hits any surface, such a ray is said to be an incident ray. After hitting the surface, this ray reflects back by making an angle with the incident ray. This is known as reflection. Thus, it changes the direction of light. Conduction is the phenomenon to allow the passage of heat or current through an object and insulation refers to resisting the flow of heat or current through the object; transparency refers to the property of an object to allow light to pass through it.

Multiple choice

Which of the following components in Dense Wavelength Division Multiplexing (DWDM) compensates the loss in optical power while the signal travels along the fibre?

  1. Terminal multiplexer

  2. Intermediate line amplifier

  3. Optical add/drop multiplexer

  4. Terminal demultiplexer

  5. Optical supervisory channel
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This component in Dense Wavelength Division Multiplexing (DWDM) compensates the loss in optical power while the signal travels along the fibre.

Multiple choice

Dry sand appears bright while wet sand appears dark because of

  1. reflection

  2. refraction

  3. optical illusion

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

When light hits dry sand, it gets scattered in many directions due to air trapped between grains, making it appear bright. Wet sand appears darker because water fills the gaps, reducing scattering and causing more light to be absorbed rather than reflected back to the observer.

Multiple choice

A rainbow is formed in the sky after rain due to ____________.

  1. dispersion of light

  2. total internal reflection of light

  3. both 1 and 2

  4. lateral displacement of light
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A rainbow is a meteorological phenomenon that is caused by reflection, refraction and dispersion of light in the water droplets, resulting in a spectrum of light appearing in the sky. It takes the form of a multi-coloured arc. Rainbows caused by sunlight always appear in the section of sky directly opposite to the sun.

Multiple choice

When a light ray is incident on the boundary separating two media of different optical densities, the light gets __________.

  1. absorbed

  2. reflected

  3. refracted

  4. partially absorbed, partially reflected and partially refracted
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This is correct as when a light ray is incident on the boundary separating two media of different optical densities, then the light gets partially absorbed, partially reflected and partially refracted.

Multiple choice

The laws of reflection are applicable to

  1. plane surface

  2. smooth surface

  3. rough surface

  4. All of above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Laws of reflection are applicable to plane and curved surfaces and rough surfaces  in case of the rough surfaces , the reflection will be diffused 

Multiple choice

Light is a form of ______________.

  1. work

  2. energy

  3. distance

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

Light is a form of electromagnetic waves and electromagnetic waves are a type of energy. We can see light almost everywhere. Light is produced and taken in by tiny packets also known as photons and correspondingly, it exhibits properties of waves and particles.

Multiple choice

Out of the following media, the minimum speed of light will be in

  1. vacuum

  2. air

  3. water

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

Light travels slowest in glass because glass has the highest refractive index (~1.5) among these options. Higher refractive index means slower speed. Vacuum has the fastest speed (n=1), followed by air (n≈1.0003), water (n≈1.33), and glass (n≈1.5).

Multiple choice

The blue colour of the sky is due to

  1. reflection of light

  2. scattering of light

  3. collection of light

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

The sky appears blue due to Rayleigh scattering - sunlight interacts with gas molecules in the atmosphere, and shorter blue wavelengths scatter more than other colors. Option B is correct. This is different from reflection (option A).

Multiple choice

A crystal capable of absorbing a radiation and re-emitting it in the form of visible light, does so after a certain small time interval of excitation. This phenomenon is called

  1. phosphorescence.

  2. fluorescence.

  3. photolysis.

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

Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation.