Interference and Diffraction MCQ Multiple Choice Questions for Practice

Q: 1. A beam of light is incident on a large block of glass. The index of refraction of the glass is greater than one. Is the wavelength of the light in the glass?

Correct Answer is: Shorter than

Q: 5. A film is said to be thin if its thickness is

Correct Answer is: Comparable with one wavelength of light

Q: 7. A monochromatic (single frequency, single wavelength) light ray in air (n = 1) enters a glass prism (n = 1.5). In the glass prism

Correct Answer is: The frequency is the same, but the wavelength is greater than in air

Q: 8. A slit of width a is illuminated by white light. For what value of a will the first minimum for red light fall at an angle of 300 wavelength of red light is 6500 Ao

Correct Answer is: 1.3 X 10 -4 cm

Q: 9. A thin film is observed in white light. The color of the film seen at a particular point depends upon

Correct Answer is: Location of observer

Q: 11. A wedge shaped thin has

Correct Answer is: Zero thickness at one end and it increasing towards other end

Q: 12. A wedge shaped thin has

Correct Answer is: Zero thickness at one end and it increasing towards other end

Q: 13. An index of refraction less than one for a medium would imply

Correct Answer is: That the speed of light in the medium is greater than the speed of light in vacuum

Q: 14. An index of refraction less than one for a medium would imply

Correct Answer is: That the speed of light in the medium is greater than the speed of light in vacuum

Q: 15. Antireflection coating is helps in which case of the following?

Correct Answer is: Minimizing the reflection of light from top surface

1. A beam of light is incident on a large block of glass. The index of refraction of the glass is greater than one. Is the wavelength of the light in the glass?

Longer than
Shorter than
The same as the wavelength of the light in the air?
None of above

2. A beam of white light is passed through a diffraction grating and the resulting spectrum is allowed to fall on a screen. Which one of the following is the color of light that undergoes the greatest deviation from its original direction? Is it

Red
yellow
Blue
violet

3. A color with a wavelength longer than that of yellow is

Red
Blue
Violet
Green

4. A diffraction grating is optically equivalent to a multiple slit system in which the number of slit, N is typically

2000/cm
3000/cm
5000/cm
1000/cm

5. A film is said to be thin if its thickness is

Much smaller than wavelength of light
Comparable with one wavelength of light
Of the order of nanometer (10^-9 m)
Of the order of Pico meter (10^-12 m)

6. A grating has 6000 lines per cm. How many orders of light of wavelength 4500 A^o can be seen?

7. A monochromatic (single frequency, single wavelength) light ray in air (n = 1) enters a glass prism (n = 1.5). In the glass prism

Both the frequency and the wavelength are the same as in air
The frequency is the same, but the wavelength is greater than in air
The frequency is the same, but the wavelength is smaller than in air
The wavelength is the same, but the frequency is greater than in air

8. A slit of width a is illuminated by white light. For what value of a will the first minimum for red light fall at an angle of 300 wavelength of red light is 6500 A^o

1.1 x 10^-3cm
1.4 X 10^-4cm
1.3 X 10^-4cm
1.6 X 10^-4 cm

9. A thin film is observed in white light. The color of the film seen at a particular point depends upon

Location of observer
Width of the source
Distance of the source
Brightness of the source

10. A wavelength is commonly measured in which one of the following units?

Radians
Angstroms
Electron volts
Seconds

11. A wedge shaped thin has

Non-uniform thickness
Zero thickness at one end and it increasing towards other end
Zero thickness at both ends
Thickness increase and decrease alternately

12. A wedge shaped thin has

Non-uniform thickness
Zero thickness at one end and it increasing towards other end
Zero thickness at both ends
Thickness increase and decrease alternately

13. An index of refraction less than one for a medium would imply

That the speed of light in the medium is the same as the speed of light in vacuum
That the speed of light in the medium is greater than the speed of light in vacuum
Refraction is not possible
Reflection is not possible

14. An index of refraction less than one for a medium would imply

That the speed of light in the medium is the same as the speed of light in vacuum
That the speed of light in the medium is greater than the speed of light in vacuum
Refraction is not possible
Reflection is not possible

15. Antireflection coating is helps in which case of the following?

Minimizing the reflection of light from top surface
To absorb and control the amount of light entering into the medium
To allow maximum light to reflect from top surface
To allow minimum light to enter into the medium

16. As a wave travels down a spring, the amplitude slowly decreases. Why does this occur?

The law of conservation of energy does not apply to waves.
The energy is spread out along the entire length of the spring.
The wave slows down as it travels along the spring.
Some energy is lost due to friction as the particles in the spring rub against each other

17. as the order increases, the width of a dark band in diffraction patterns

Increases
Decreases
Does not change
becomes infinity

18. Coherent light of a single frequency passes through a double slit with a separation d, to produce a pattern on a screen as distance D from the slits. What would cause the separation between adjacent minima on the screen to increase?

increase the index of refraction of the medium in which the setup is immersed
increase the separation d between the slits
increase the distance
increase the frequency of the incident light

19. Colors in thin films are because of

Dispersion
Compton effect
Interference
Diffraction

20. Diffraction due to circular aperture If a light passes through a small pinhole, and incident on a screen. What will be observed on the screen?

A sharp bright point of the width equal to width the pinhole
A bright point of the width equal to width the pinhole but of less intensity
A bright ring at the centre surrounded by alternate dark and bright rings
A diffused bright point

21. Diffraction is special type of

Reflection
Refraction
Interference
Polarization

22. Extended source is needed in

Youngs double slit experiment
Bi prism Experiment
Newtons Ring Experiment
None of them

23. Find the maximum value of resolving power of a grating 3 cm wide having 5000 lines per cm, if the wavelength of light used is 5890 A^o.

40000
45000
4500
5000

24. For all transparent material substances, the index of refraction

is less than 1
is greater than 1
is equal to 1
Could be any of the given answers; it all depends on optical density

25. Fraunhofer diffraction at a Plane Grating. What is the meaning of grating element for a diffraction grating?A It is the width of a single slit

It is the width of the opaque space
It is the distance between two slits
It is the width of diffraction grating

26. Fraunhofer diffraction is observed when

Only screen is placed at finite distance
source is placed at finite distance
neither source nor screen is at finite distance
None of these

27. Fresnels type diffraction is observed when

Only screen is placed at finite distance
Only source is placed at finite distance
Both source and screen are at finite distance
Neither source nor screen is at finite distance

28. Fringe spacing is defined as the distance between two Consecutive

Crests
Bright fringes only
Dark fringes only
Bright or dark fringes

29. How the intensity of secondary maxima varies in case of Fraunhofer diffraction pattern for single slit?

Intensity of secondary maxima decreases on either sides
Intensity of secondary maxima remains constant on either side
Intensity increases and decreases alternately
Intensity of secondary maxima increases on either sides

30. If we narrow the distance between two slits in Youngs experiment the fringes width

Increases
Decreases
Remains same
becomes zero

Welcome to our Interference and Diffraction MCQs section, designed to help students and exam aspirants master these fundamental concepts in physics. Whether you're preparing for school exams, competitive tests, or job interviews, these multiple-choice questions are essential for your success.

About Interference and Diffraction MCQ Questions

Interference and Diffraction MCQs cover key concepts such as wave interference, diffraction patterns, and the behavior of light waves. These questions are crafted to test your understanding of how waves interact and how they diffract when passing through narrow openings or around obstacles.

Why Practice Interference and Diffraction Objective Questions?

Practicing these objective questions helps you solidify your knowledge, prepare for various exams, and enhance your problem-solving skills. They are particularly useful for revising core concepts, boosting confidence, and ensuring you are well-prepared for both academic and professional challenges.

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