Refraction through a Prism MCQ Quiz - Objective Question with Answer for Refraction through a Prism - Download Free PDF

Last updated on Jul 8, 2025

Latest Refraction through a Prism MCQ Objective Questions

Refraction through a Prism Question 1:

- amglogisticsinc.net

Two parallel light beams, labeled P and Q, are incident perpendicularly on a prism. These beams are separated by a distance d and consist of coherent monochromatic waves of wavelengths 4000 Å and 5000 Å, respectively. Each beam is internally coherent at its own wavelength. The wavelength-dependent refractive index μ(λ) of the prism material is given by: μ(λ) = 1.20 + b / λ2, where λ is in Ångströms and b is a positive constant. It is observed that total internal reflection occurs at the face AC of the prism for only one of the wavelengths, while the other passes through. If the angle of incidence at face AC is such that sin θ = 0.8, determine the value of α where b = α × 10 Afor this condition.

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Answer (Detailed Solution Below) 8

Refraction through a Prism Question 1 Detailed Solution

Calculation:

For total internal reflection to occur, the condition is:

sin θ > 1 / μ(λ)

Given: sin θ = 0.8

⇒ Total internal reflection just occurs when μ(λ) = 1 / 0.8 = 1.25

We use the given refractive index formula:

μ(λ) = 1.20 + b / λ2

Now, plug in λ = 4000 Å for which total internal reflection occurs:

1.25 = 1.20 + b / (4000)2

⇒ b / (1.6 × 107) = 0.05

⇒ b = 0.05 × 1.6 × 107 = 8 × 105

Answer: b = 8 × 105

KEY: b = 8 × 105

Refraction through a Prism Question 2:

 


- amglogisticsinc.net A parallel beam of light enters from air and strikes the side PR of a right-angled triangular prism. The prism has a refractive index of n = 2. The light undergoes total internal reflection at face QR such that the ray is grazing the side PR . What is the angle of the prism?

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  1. 21
  2. 23
  3. 25
  4. 27

Answer (Detailed Solution Below)

Option 2 : 23

Refraction through a Prism Question 2 Detailed Solution

Calculation:

At the interface of PR the incidence angle is θ  and refracted angle is θ'

thus , sinθ = n sinθ'         (1)

And at interface QR, The snell's laws is 

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n cosθ'' = 1                     (1) 

⇒ sinθ'' = √(1- 1/n2)  

from figure θ + θ' = θ'' ⇒ θ' = θ'' - θ 

⇒ sinθ = n(sinθ'' cosθ - cosθ'' sinθ )

⇒ sinθ = (√3 / 2)cosθ -  sinθ 

⇒ 1= (√3 / 2) cotθ -1 

⇒ cotθ = 4 /√3 = θ ≈ 23 

Refraction through a Prism Question 3:

A ray of light suffers minimum deviation when incident on a prism having angle of the prism equal to 60°. The refractive index of the prism material is √2. The angle of incidence (in degrees) is _____. 

Answer (Detailed Solution Below) 45

Refraction through a Prism Question 3 Detailed Solution

Calculation:

Given: Angle of prism A = 60°, Refractive index μ = √2, Minimum deviation δm

At minimum deviation, i = e, and:

μ = sin((A + δm)/2) / sin(A/2)

Substitute values:

μ = √2 = sin((60° + δm)/2) / sin(30°)

√2 = sin((60° + δm)/2) / (1/2)

⇒ sin((60° + δm)/2) = √2 × (1/2) = 1/√2

⇒ (60° + δm)/2 = 45° ⇒ 60° + δm = 90° ⇒ δm = 30°

Now use: δm = 2i − A

30° = 2i − 60° ⇒ 2i = 90° ⇒ i = 45°

Final Answer: 45°

Refraction through a Prism Question 4:

A ray of light is incident from air on a glass plate having thickness √3 cm and refractive index √2. The angle of incidence of a ray is equal to the critical angle for glass-air interface. The lateral displacement of the ray when it passes through the plate is ___ × 10-2 cm. (given sin 15° = 0.26) 

Answer (Detailed Solution Below) 52

Refraction through a Prism Question 4 Detailed Solution

Calculation:

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sin c = 1 / √2

⇒ c = 45°

sin c = μ sinθ

⇒ 1 / √2 = √2 × sinθ

⇒ θ = 30°

Lateral displacement:

x = t × sin(i - r) × sec r

⇒ x = √3 × sin(45° - 30°) × sec 30°

⇒ x = √3 × 0.26 × (2 / √3)

⇒ x = 0.52 cm = 52 × 10-2 cm

Refraction through a Prism Question 5:

What is the angle that is formed between the incident ray and the normal line called?

  1. Angle of deviation
  2. Angle of incidence
  3. Angle of refraction
  4. Angle of reflection

Answer (Detailed Solution Below)

Option 2 : Angle of incidence

Refraction through a Prism Question 5 Detailed Solution

Concept:

When a ray of light strikes a surface, the angle formed between the incoming ray (incident ray) and the normal (an imaginary line perpendicular to the surface) is called the angle of incidence. This is a fundamental concept in the laws of reflection and refraction in optics.

Definition:

Angle of Incidence – The angle between the incident ray and the normal to the surface at the point of incidence.

Top Refraction through a Prism MCQ Objective Questions

Name the scientist who first used a glass prism to obtain the spectrum of sunlight

  1. C. V. Raman
  2. Lord Rayleigh
  3. Issac Newton
  4. S. Chandrasekhar

Answer (Detailed Solution Below)

Option 3 : Issac Newton

Refraction through a Prism Question 6 Detailed Solution

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CONCEPT:

  • Dispersion of light: The splitting of a composite beam of light into its constituent colours is called dispersion of light.

F1 Jitendra Deepak 03.04.2020 D8

  • The dispersion of white light occurs because the colours of white light travel at different speeds through the glass prism.
    • The band of seven colours is known as the spectrum of light.
    • The dispersion was discovered by Sir Issac Newton.
    • Newton discovered that light is made up of seven different colours.

EXPLANATION:

  • From the above, it is clear that Issac Newton was the first to use a glass prism to obtain the spectrum of sunlight. Therefore option 3 is correct.

The process of splitting white light into its seven constituent colours is called

  1. Refraction 
  2. Dispersion
  3. Scattering
  4. Reflection

Answer (Detailed Solution Below)

Option 2 : Dispersion

Refraction through a Prism Question 7 Detailed Solution

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CONCEPT:

Term Definition Diagram
Refraction When a ray of light passes from one medium to another it suffers a change in direction at the boundary of two media is called refraction. F1 J.K 8.5.20 Pallavi D3
Dispersion The splitting of white light, when it passes through a glass prism into its constituent spectrum is known as the dispersion of light. F1 J.K 12.6.20 Pallavi D3
Scattering Scattering of light: The phenomenon in which the light ray is redirected in all other directions on passing through particles of dimensions comparable to the wavelength of the light used is called scattering of light. F1 J.K 8.5.20 Pallavi D1
Reflection The phenomena in which a light ray is sent back into the same medium from which it is coming, on interaction with the boundary, is called reflection. F1 J.K 12.6.20 Pallavi D2

EXPLANATION:

  • The process of splitting white light into its seven constituent colours is called dispersion. So option 2 is correct.

The refractive indices of Kerosene, Turpentine and water are 1.44, 1.47 and 1.33 respectively. Light will have maximum speed in:

  1. Kerosene
  2. Turpentine
  3. Water
  4. Speed remains same for all

Answer (Detailed Solution Below)

Option 3 : Water

Refraction through a Prism Question 8 Detailed Solution

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The correct answer is Water.

Key Points

  • Refractive Index is the ratio of the light's speed in a vacuum to its speed in a specified medium.
  • It is a dimensionless quantity.
  • Formulae are given for the refractive index
    • n = c/v
    • n = refractive index
    • c = velocity of light in a vacuum.
    • v = velocity of light in a specified medium.
  • From the given formulae we get, the Refractive index is the inverse relation to Light's speed.
  • The refractive index of the material is high, then the light's speed will be low and vice-versa.
  • In the given question, the refractive indices of Kerosene, Turpentine, and water are 1.44, 1.47 and 1.33, respectively.
  • So, the water has the lowest refractive index among all so, the speed of light will be maximum in water.
  • Turpentine has the highest refractive index, so the speed of light will be low in the Turpentine.

The refractive index of a thin prism of prism angle 5° is 1.4. Find the angle of deviation of light ray falling on this prism.

Answer (Detailed Solution Below)

Option 2 : 2°

Refraction through a Prism Question 9 Detailed Solution

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Concept:

Dispersion of light:

  • The phenomenon in which a white light ray when falls on a prism gets separated into its component colors is called as dispersion of light.
  •  Different colors of different wavelength experience different degree of deviation and hence when put through refraction, white light splits into its constituent colors.
  • When light rays fall on the prism then there is deviation in the path of the ray after refraction through prism.
  • For a thin prism deviation angle is very small.

The deviation angle for a thin prism of prism angle A is given by:

δ = (μ - 1) A

Where μ is the refractive index of the Prism

Explanation:

Given that;

Refractive index = μ = 1.4

Angle of prism = A = 5°

Angle of deviation = δ = (μ - 1) A = (1.4-1) × 5 = 2° 

When white light passes through a hollow prism, then 

  1. there is both dispersion and deviation
  2. deviation but no dispersion
  3. there is no dispersion and no deviation
  4. dispersion but no deviation

Answer (Detailed Solution Below)

Option 3 : there is no dispersion and no deviation

Refraction through a Prism Question 10 Detailed Solution

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CONCEPT:

  • Dispersion of light: The phenomenon in which a white light ray when falls on a prism get separated into its component colors is called dispersion of light.
  • When light rays fall on the prism then there is a deviation in the path of the ray after refraction through the prism

EXPLANATION:

 

F1 Jitendra.K 03-09-2020 Savita D1

  • When the light rays enter the first wall of the hollow prism then it bends towards normal to the surface because it enters the denser medium.
  • Just the opposite will happen when it leaves the first wall and the ray will bend away from normal because it enters a lighter medium with exactly the same angle.
  • Similarly, when the light ray enters the wall on the other side, on the way towards the exit, it bends toward normal.
  • And finally bends away from the normal at the exit.
  • Thus we find that there is no dispersion and no deviation of light rays. So option 3 is correct.

Splitting of light into its colours is known as?

  1. Total internal refraction
  2. Refraction
  3. Diffraction
  4. Dispersion

Answer (Detailed Solution Below)

Option 4 : Dispersion

Refraction through a Prism Question 11 Detailed Solution

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The correct answer is Dispersion.

CONCEPT:

  • Total Internal reflection: The total reflection of light from a higher refractive index medium to back in its medium at an angle more than a critical angle known as total internal reflection.

 

F1 J.K 12.6.20 Pallavi D4

  • Refraction: When a ray of light passes from one medium to another it suffers a change in direction at the boundary of two media is called refraction.
  • The change in direction because the speed of light travels at different speeds in different mediums.
  • The Refractive Index of a medium defines that it is denser or rarer

 F1 J.K 8.5.20 Pallavi D3

  • Diffraction: In diffraction, when a light wave encounters an obstacle or a slit, it bends around the corners of the obstacle or aperture. Hence, it is a wave phenomenon.
  • Dispersion of light: The splitting of white light, when it passes through a glass prism into its constituent spectrum is known as the dispersion of light.
  • Sunlight splits into 7 colors – Violet, Indigo, Blue, Green, Yellow, Orange, and Red (VIBGYOR).
  • A rainbow is a natural phenomenon showing dispersion.

F1 J.K 12.6.20 Pallavi D3

EXPLANATION:

From the above discussion, we can say that

  • Splitting of light into its constituent colours is known as Dispersion of light. So option 4 is correct.

The dispersion is-

  1. bending of light ray at a corner
  2. reflection of light rays from a surface
  3. bending of light ray towards normal when it travels from one medium to another
  4. splitting of white light into its constituent colours

Answer (Detailed Solution Below)

Option 4 : splitting of white light into its constituent colours

Refraction through a Prism Question 12 Detailed Solution

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The correct answer is splitting of white light into its constituent colors.

CONCEPT:

  • Dispersion of light: The splitting of a composite beam of light into its constituent colors is called dispersion of light.

F1 Jitendra 22.9.20 Pallavi D2

  • The dispersion of white light occurs because the colors of white light travel at different speeds through the glass prism.
    • The band of seven colors is known as the spectrum of light.
    • The dispersion was discovered by Sir Issac Newton.
    • Newton discovered that light is made up of seven different colors.

EXPLANATION:

  • From the above, it is clear that the splitting of a composite beam of light into its constituent colors is called dispersion of light. Therefore option 4 is correct.

Light splits into different colours when passes through diamond. This is an example of _______.

  1. Reflection of light
  2. Interference of light
  3. Total internal reflection of light
  4. Dispersion of light

Answer (Detailed Solution Below)

Option 4 : Dispersion of light

Refraction through a Prism Question 13 Detailed Solution

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Answer : (4)

CONCEPT:

  • Dispersion of light: The phenomenon in which a white light ray when falls on a prism get separated into its component colors is called dispersion of light.

F1 Jitendra Deepak 03.04.2020 D8

  • The seven constituent colors are Violet, Indigo, Blue, Green, Yellow, Orange, and Red.
  • Some examples of Dispersion of light are the formation of the rainbow, dispersion of white light in a prism, dispersion of light on a CD, etc.

EXPLANATION:

  • The diamond act like a prism. The splitting up of white light into its 7 constituent colors is called dispersion of light. So option 4 is correct.
Phenomenon Examples
Reflection of light When one sees in a mirror, sunlight casts sharp shadows, etc
Interference of light A film of oil floating in the water, a thin film of a soap bubble, etc
Total Internal Reflection Mirage, Optical fiber

Which of the colour of light is maximum deviated when passed through a prism?

  1. Red
  2. Voilet
  3. Blue
  4. Green

Answer (Detailed Solution Below)

Option 2 : Voilet

Refraction through a Prism Question 14 Detailed Solution

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CONCEPT:

Dispersion of light:

Set 9 Om 20Q -Hindi.docx 3

  • Dispersion of light is the phenomenon of splitting of a beam of white light into its constituent colours on passing through a prism.
  • The band of seven colours so obtained is called the (visible) spectrum.
  • The dispersion of white light occurs because the colours of white light travel at different speeds through the glass prism.

EXPLANATION:

  • When the dispersion of white light takes place through a prism, the maximum deviation is suffered by violet colour and minimum deviation suffered red colour. Therefore option 2 is correct.

Why does dispersion occur when white light which is a mixture of seven colours passes through a glass prism?

  1. 7 colours of white light travels at different speeds through a glass prism
  2. 7 colours are refracted at same speed.
  3. 7 colours are reflected by prism
  4. The white light scatters the 7 colours throughout the prism

Answer (Detailed Solution Below)

Option 1 : 7 colours of white light travels at different speeds through a glass prism

Refraction through a Prism Question 15 Detailed Solution

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CONCEPT:

Set 9 Om 20Q -Hindi.docx 3

  • Dispersion of light: The splitting of a composite beam of light into its constituent colors is called dispersion of light. 
    • The dispersion of white light occurs because the colors of white light travel at different speeds through the glass prism.
    • The dispersion was discovered by Sir Issac Newton.
    • Newton discovered that light is made up of seven different colors.

EXPLANATION:

  • The dispersion of white light occurs because colors of white light travel at different speeds through the glass prism. So option 1 is correct.
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