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. 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?

0.49 mm0.34 mm0.17 mm0.23 mm

2. 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?

2: 15: 41: 24: 5

3. 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 m0.004 m0.005 m0.006 m

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

FalseMaybeDon't KnowTrue

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

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

6. In YDS, the width of the fringes obtained from a light of wavelength 500 nm is 3.6 mm. What is the fringe width id the apparatus is immersed in a liquid of refractive index 1.2?

3 mm2.6 mm2 mm3.2 mm

7. 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 ___________

4000 Å7000 Å6000 Å5000 Å

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

Fringe width decreasesColored fringesFringe width increasesThe bright and dark fringes will change position

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

Remains sameDoublesHalvesFour-times

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

2nλnλ(2n + 1) λ/2(n + 1) λ/2

11. The main principle used in Interference is _____________

Superposition PrincipleHeisenberg’s Uncertainty PrincipleQuantum MechanicsFermi Principle

12. 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?

1.25 mm2.78 mm2.5 mm3.25 mm

13. 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?

3 mm1 mm4 mm2 mm

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

HyperbolicEllipticalCircularStraight

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

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

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

IntenseIncoherentCoherentBright

17. Which phenomenon is observed in the following figure?

Newton’s RingsRefractionWedge-Shaped filmDestructive Interference

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

TrueFalseDon't KnowMaybe

19. 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 nm198.3 nm214.3 nm179.6 nm

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

DoubleFour TimesOne-FourthHalf

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

A thick filmExcessively thin filmSoap bubbleWedge Shaped film

22. Zero order fringe can be identified using ____________

Yellow lightMonochromatic lightAchromatic lightWhite light

23. 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?

1.051.251.351.15

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

MaybeTrueDon't KnowFalse

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

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