Thomas Young's double-slit experiment in 1801 was the first to demonstrate the phenomenon of light interference. The experiment involved shining a coherent light source, such as a laser, through two narrow slits cut into a screen. The light waves passing through the slits interfered with each other, creating a wave-like pattern on the screen.  Young observed that when the two beams of light recombined, the combined beam showed a pattern of light and dark fringes. He concluded that the fringes resulted from the fact that when the beams recombine their peaks and troughs may not be in... Show more

Thomas Young's double-slit experiment in 1801 was the first to demonstrate the phenomenon of light interference. The experiment involved shining a coherent light source, such as a laser, through two narrow slits cut into a screen. The light waves passing through the slits interfered with each other, creating a wave-like pattern on the screen. 

Young observed that when the two beams of light recombined, the combined beam showed a pattern of light and dark fringes. He concluded that the fringes resulted from the fact that when the beams recombine their peaks and troughs may not be in phase. 
The experiment played a major role in the general acceptance of the wave theory of light. Further experiments showed that light actually behaves as both a wave and as particles, revealing its quantum nature. 

Related Test: Engineering Physics Practice Test: Introduction to Optics

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Engineering Physics Practice Test: Light Inference and Young’s Experiment

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25 Questions

1. A Young’s double slit apparatus is immersed in a liquid of refractive index 1.25. What is the ratio of the fringe width in air and liquid?

5: 42: 11: 24: 5

2. Interference is observed only when the phase difference between the two waves is zero.

FalseTrueMaybeDon't Know

3. When a thin plate of refractive index 1.5 is placed in the path of one of interfering beams of Michaelson Interferometer, a shift of 30 fringes is observed. If the thickness of plate is 0.018 mm, the wavelength of the used light is ___________

5000 Å7000 Å4000 Å6000 Å

4. A thin layer of colorless oil is spread over water in a container (μ = 1.4). If the light of wavelength 640 nm is absent in the reflected light, what is the minimum thickness of oil layer?

207.6 nm214.3 nm179.6 nm198.3 nm

5. Two narrow and parallel slits 0.08 cm apart are illuminated by a light of frequency 6 X 10¹¹ kHz. At what distance from the slits should the screen be placed to obtain fringe width of 0.6 mm?

0.98 m1.28 m1.06 m1.74 m

6. According to stoke’s law, the expression for maxima is: 2μtcosr = ____________

2nλ(2n + 1) λ/2nλ(n + 1) λ/2

7. In Young’s Double Slit experiment, the angular width of the fringe is 0.1^o. If the light used has a wavelength of 600 nm, what is the spacing between the slits?

0.17 mm0.49 mm0.34 mm0.23 mm

8. A thin sheet of refractive index 1.5 and thickness 1 cm is placed in the path of light. What is the path difference observed?

0.003 m0.005 m0.006 m0.004 m

9. Which phenomenon is observed in the following figure?

Destructive InterferenceWedge-Shaped filmNewton’s RingsRefraction

10. What kind of sources are required for Young’s Double Slit experiment?

IntenseIncoherentCoherentBright

11. In Newton’s ring experiment, the diameter of the 10^th ring changes from 1.40 to 1.23 cm when a liquid is introduced between the lens and glass plate. What is the refractive index of the liquid?

1.151.251.051.35

12. The shape of the fringes observed in interference is ____________

EllipticalHyperbolicStraightCircular

13. There is no effect on the interference pattern when the width of the slit is increased.

Don't KnowFalseTrueMaybe

14. Which of the following does not show any interference pattern?

Excessively thin filmSoap bubbleWedge Shaped filmA thick film

15. When Two waves of same amplitude add constructively, the intensity becomes _____________

Four TimesHalfOne-FourthDouble

16. Young’s Double Slit Experiment was conducted in ______________

1802188919301925

17. In Young’s Double Slit Experiment, if instead of monochromatic light white light is used, what would be the observation?

Colored fringes will be observed with a white bright fringe at the centerThe shape of the pattern will change from hyperbolic to circularThe pattern will not be visibleThe bright and dark fringes will change position

18. The following intensity variation is observed in a Young’s Double Slit Experiment.

FalseMaybeDon't KnowTrue

19. A thin sheet of refractive index 1.25 and thickness 0.5 cm is placed in the path of light from one source in the Young’s double slit experiment. What is the path difference observed?

2.5 mm2.78 mm1.25 mm3.25 mm

20. Zero order fringe can be identified using ____________

Achromatic lightWhite lightMonochromatic lightYellow light

21. The main principle used in Interference is _____________

Fermi PrincipleHeisenberg’s Uncertainty PrincipleSuperposition PrincipleQuantum Mechanics

22. When a plate of thickness 0.05 mm is placed in the path of a Michaelson Interferometer, a shift of 100 fringes is observed for a light of wavelength 5000 Å. What is the refractive index of the plate?

2.5121.5

23. The interference pattern of soap bubble changes continuously.

MaybeDon't KnowFalseTrue

24. The shape of the pattern depends on the ____________

Shape of the slitWavelength of lightDistance between the slits and the screenDistance between the slits

25. What change is observed when the whole pattern is immersed in water?

Fringe width decreasesFringe width increasesThe bright and dark fringes will change positionColored fringes