# MCQ on Interference in Wave Optics

## MCQ on Interference in Wave Optics

MCQ on Interference in Wave Optics, Multiple Choice Questions on Interference in Wave Optics, Engineering Physics MCQ, Objective Question with answer on Interference in Wave Optics, Interference MCQ, Wave Optics MCQ, Engineering MCQ

### Multiple Choice Questions

Q.1. The sources of light are said to be coherent if the waves produced by them have the same:

• wavelength
• amplitude
• wavelength and a constant phase difference
• amplitude and the same wavelength

Answer: wavelength and a constant phase difference

Q.2. Interference occurs in:

• longitudinal waves only
• transverse waves only
• electromagnetic waves only
• all above waves

Q.3. The phenomenon of interference is used to prove that light is:

• longitudinal
• transverse
• stationary wave
• quantized

Q.4. In interference with two coherent sources, the fringe width varies:

• directly as wavelength
• inversely as wavelength
• directly as the separation between slits
• inversely as the distance between the slits and screen

Q.5. In a Fresnel’s bipriment, the central fringe is:

• bright
• dark
• first bright and then dark
• first dark and then bright

Quantum Physics MCQ

Q.6. In Young’s double slit experiment if the slit widths are in the ratio 1 : 9, the ratio of the intensity at minima to that at maxima will be:

• 1
• 1/9
• 1/4
• 1/3

Q.7. Two waves having the intensities in the ratio of 9:1 produce interference. The ratio of maximum to minimum intensity is equal to:

• 10 : 8
• 9 : 1
• 4 : 1
• 2 : 1

Q.8. Fringe width in Young’s double slit experiment, increases when:

• separation between sources increases
• distance between source and screen increases
• wavelength of light decreases
• do not change

Answer: distance between source and screen increases

Q.9. Actual shape of interference fringes is:

• parabolic
• hyperbolic
• straight
• none

Q.10. Fringe width in case of wedge shape film is:

• directly proportional to the refractive index between wedge film
• directly proportional to the wavelength of light
• directly proportional to the angle of wedge
• inversely proportional to the thickness of the film

Answer: directly proportional to the wavelength of light

Q.11. Newton’s ring illustrates the phenomenon of:

• interference
• diffraction
• polarization
• dispersion

Q.12. Which of the following phenomena produces the colours in soap bubble?

• interference
• diffraction
• polarization
• dispersion

Q.13. Two coherent sources whose intensity ratio is 81 : 1 produce interference fringes. The ratio of maximum to minimum intensity of the fringe system is:

• 9 : 1
• 25 : 6
• 16 : 25
• 5:4

Q.14. In Newton’s ring experiment which type of source is used:

• mercury lamp
• sodium lamp
• incandescent lamp
• fluorescent lamp

Q.15. Newton’s rings are:

• locus of points of equal thickness
• locus of points of equal inclination
• locus of points of equal thickness and of equal inclination
• none of the above

Answer: locus of points of equal thickness

Q.16. Which statement is true for Newton’s ring?

• diameter is independent of wavelength of light
• locus of points of equal inclination
• central rings are broad and peripheral rings are closer
• none of the above

Q.17. In Newton’s ring arrangement the diameter of 10th dark ring changes from 1.5 m to 1.27 cm when a liquid is introduced between the lens and the glass plate. The refractive index of the liquid is:

• 0.847
• 0.717
• 1.18
• 1.39

Q.18. In Newton’s rings arrangement with air film in reflected light the diameter of no ring is Dn. If the air is replaced by liquid film of refractive index µ, the diameter of nth fringe will become:

• $\sqrt{\mu }$
• $\frac{1}{\sqrt{\mu }}$
• $\frac{1}{\mu }$
• $\mu$  times

Answer: $\frac{1}{\sqrt{\mu }}$

Q.19. In Newton’s ring arrangement the diameter of rings formed is proportional to:

• $\lambda$
• $\sqrt{\lambda }$
• $\frac{1}{\sqrt{\lambda }}$
• $\frac{1}{\lambda}$

Answer: $\sqrt{\lambda }$

Q.20. In Newton’s ring due to reflected light, the path difference at centre is:

• $t\lambda$
• $2t+\frac{\lambda }{2}$
• $\lambda$
• $\frac{\lambda }{2}$

Answer: $\frac{\lambda }{2}$

Q.21. If water drops (µ =1.33) are introduced between the plate and the lens in the Newton’s ring experiment, the diameter of rings will:

• contract to 0.866 times
• expands to 0.866 times
• contract to 0.751 times
• expands to 0.751 times

Q.22. The diameter of dark ring in Newton’s ring is:

• directly proportional to square root of natural numbers
• inversely proportional to square root of natural numbers
• directly proportional to square root of even numbers
• directly proportional to square root of odd numbers

Answer: directly proportional to square root of natural numbers

Q.23. When the liquid is introduced between the lens and the plate, the diameters of the rings:

• decrease
• increase
• remain same
• none of these

Q.24. Light beam after reflection from an optically denser medium undergoes a phase changes of:

• π
• 0
• π/2