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

Glass, cellophane and plastic sheet are examples of __________ objects.

  1. transparent

  2. opaque

  3. translucent

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

 

Multiple choice

When sunlight falls on a soap bubble bright colours are seen. They are produced by:

  1. dispersion

  2. interference

  3. refraction

  4. pigments in the soap

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

The colorful patterns on soap bubbles are caused by thin film interference. When white light strikes the thin soap film, some waves reflect from the outer surface while others penetrate and reflect from the inner surface. These reflected waves interfere constructively or destructively depending on film thickness, creating colors. Dispersion splits light into colors in prisms, refraction bends light, and soap has no pigments.

Multiple choice

Sky appears blue due to which scientific phenomenon?

  1. Interference of light.

  2. Dispersion of light.

  3. Refraction of light.

  4. Scattering of light.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The sky appears blue due to Rayleigh scattering - shorter blue wavelengths scatter more than longer red wavelengths when sunlight hits atmospheric molecules. This scattered blue light reaches our eyes from all directions.

Multiple choice

Which of the following is/are not condition(s) for the formation of a shadow?

(a) There must be a source of light (b) There must be a transparent body to pass the light (c) There must be an opaque screen to receive the shadow

  1. Only a

  2. Both a and b

  3. Only c

  4. Only b

  5. Both a and c
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This is the correct option, as this is not a condition for the formation of a shadow. There must be an opaque body to obstruct the light, and not a transparent body to pass the light.

Multiple choice

Which of the following statements is/are false? (a) When the light falls on any object, it bounces off from the surface of the object in all directions. (b) The speed of light is 300,000 m/s. (c) Light is an invisible energy, which cannot be seen, but it causes us to see things.

  1. Only a

  2. Both a and b

  3. Only b

  4. Only c

  5. Both a and c
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This is the correct option. The speed of light is not 300,000 m/s, but it is 300,000 km/s. The light from the sun reaches the earth in 8.33 minutes.

Multiple choice

A coin is dropped at refractive index of 4/3. The real depth of coin is 28 cm. The coin would be apparently appear to be at the depth of

  1. 80 cms

  2. 25 cms

  3. 20 cms

  4. 21 cms
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When light travels from a denser medium (water) to a rarer medium (air), it bends away from the normal, making objects appear shallower. The apparent depth is calculated by dividing the real depth by the refractive index: 28 cm ÷ (4/3) = 21 cm. Option A (80 cm) incorrectly multiplies by the refractive index, while B (25 cm) and C (20 cm) are calculation errors.

Multiple choice

What is nephelometry?

  1. Lambert-Beer law

  2. Scattering of light by particulate solution

  3. Deffraction of light

  4. Decreased intensity of light
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Nephelometry is based on the principle that particles suspended in a solution scatter light. The intensity of scattered light is directly proportional to the concentration of particles. It is commonly used for measuring proteins and other analytes in immunonephelometry assays.

Multiple choice

Nephelometry is:

  1. Lambert-Beer law

  2. Scattering of light by particulate solution

  3. Defraction of light

  4. Decreased intensity of light
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Nephelometry measures the scattering of light by particles suspended in a solution. The scattered light intensity is proportional to particle concentration. It is distinct from turbidimetry (which measures decreased light transmission) and spectrophotometry (which measures light absorption).

Multiple choice

When a ray of light is transmitted from air to glass the frequency

  1. increases and wavelengh decreases

  2. decreases and wavelength increases

  3. is unaltered but the wavelength decreases

  4. is unaltered but the wavelength increases
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The frequency of light remains constant when it passes from one medium to another because it's determined by the source. However, the wavelength decreases in glass because light travels slower in the denser medium (v = f×λ, and n=c/v). The relationship is: λ_glass = λ_air / n_glass.

Multiple choice

Which phenomenon causes an air bubble in water to shine?

  1. Dispersion

  2. Refraction

  3. Diffraction

  4. Total internal reflection
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An air bubble shines due to total internal reflection - light entering the bubble at an angle greater than the critical angle gets completely reflected inside, creating a shiny appearance. Dispersion splits light into colors (like rainbows), refraction bends light passing through different media, and diffraction spreads light around obstacles.

Multiple choice

Aquatic photodiffraction is:

  1. euphotic, disphotic, and aphotic

  2. aphotic, euphotic and disphotic

  3. euphotic, aphotic and disphotic

  4. euphotic, disphotic and aphotic

  5. none of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Different photodiffraction zones are euphotic, disphotic and aphotic.