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. Which phenomenon is observed in the following figure?

Wedge-Shaped filmRefractionNewton’s RingsDestructive Interference

2. 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?

0.004 m0.005 m0.006 m0.003 m

3. Zero order fringe can be identified using ____________

White lightAchromatic lightMonochromatic lightYellow light

4. The visibility of fringes is given by the expression ___________

lmax/lminlmin/lmaxlmin + lmax / lmin – lmaxlmin – lmax / lmin + lmax

5. 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 Å4000 Å7000 Å6000 Å

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

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

7. The interference pattern of soap bubble changes continuously.

FalseDon't KnowTrueMaybe

8. 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?

12.51.52

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

The bright and dark fringes will change positionFringe width decreasesFringe width increasesColored fringes

10. 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?

1.28 m0.98 m1.74 m1.06 m

11. 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?

214.3 nm179.6 nm198.3 nm207.6 nm

12. If instead of monochromatic light white light is used for interference of light, what would be the change in the observation?

The pattern will not be visibleColored fringes will be observed with a white bright fringe at the centerThe bright and dark fringes will change positionThe shape of the pattern will change from hyperbolic to circular

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

CoherentIncoherentIntenseBright

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

1930180219251889

15. The main principle used in Interference is _____________

Quantum MechanicsFermi PrincipleHeisenberg’s Uncertainty PrincipleSuperposition Principle

16. If the distance between the two slits is doubled, the fringe width _________

Remains sameHalvesFour-timesDoubles

17. 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

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

CircularEllipticalStraightHyperbolic

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

nλ(2n + 1) λ/2(n + 1) λ/22nλ

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

Wedge Shaped filmSoap bubbleExcessively thin filmA thick film

21. 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

22. In a Young’s double slit experiment, the distance between the two slits is 0.5 mm and the distance between the screen and the slits is 1 m. When a light of wavelength 500 nm is incident on the slits, what would be distance between the two second bright fringes?

2 mm1 mm4 mm3 mm

23. The shape of the pattern depends on the ____________

Wavelength of lightShape of the slitDistance between the slits and the screenDistance between the slits

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

Don't KnowTrueMaybeFalse

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

One-FourthFour TimesDoubleHalf