Young's Double Slit Experiment - NEET Physics Questions
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Young's Double Slit Experiment

Question 11: moderate

In Young’s double slit experiment, one of the slit is wider than other, so that the amplitude of the light from one slit is double of that from other slit. If Im be the maximum intensity, the resultant intensity I when they interfere at phase difference Φ is given by :

1. \[\frac{I_{m}}{5}\left( 1+4cos^{2}\frac{\phi}{2}\right)\]
2. \[\frac{I_{m}}{9}\left( 1+8cos^{2}\frac{\phi}{2}\right)\]
3. \[\frac{I_{m}}{9}\left( 4+5cos^{2}\frac{\phi}{2}\right)\]
4. \[\frac{I_{m}}{3}\left( 1+2cos^{2}\frac{\phi}{2}\right)\]
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Question 12: easy

Two coherent sources of light can be obtained by :

1. Two different lamps
2. Two different lamps but of the same power
3. Two different lamps of same power and having the same colour
4. None of the above
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Question 13: easy

Two identical light waves, propagating in the same direction, have a phase difference δ. After they superpose, the intensity of the resulting wave will be proportional to :

1. cos δ
2. cos (δ/2)
3. cos² (δ/2)
4. cos² δ
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Question 14: easy

If the amplitude ratio of two sources producing interference is 3 : 5, the ratio of intensities at maxima and minima is :

1. 25 : 16
2. 5 : 3
3. 16 : 1
4. 25 : 9
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Question 15: moderate

In the Young’s double slit experiment, the ratio of intensities of bright and dark fringes is 9. This means that :-
(A) The intensities of individual sources are 5 and 4 units respectively
(B) The intensities of individual sources are 4 and 1 units respectively
(C) The ratio of their amplitudes is 3
(D) The ratio of their amplitudes is 2

1. B, D
2. B, C
3. A, C
4. A, D
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Question 16: moderate

In a Young’s double slit experiment, the fringe width is found to be 0.4 mm. If the whole apparatus is immersed in water of refractive index 4/3 without disturbing the geometrical arrangement, the new fringe width will be :

1. 0.30 mm
2. 0.40 mm
3. 0.53 mm
4. 450 micron
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Question 17: moderate

In a Young’s double slit experiment the intensity at a point where the path difference is λ/6 (λ being the wavelength of the light used) is I. If I0 denotes the maximum intensity, I/I0 is equal to :

1. 1/√2
2. √3/2
3. 1/2
4. 3/4
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Question 18: moderate

In the Young’s double slit experiment, for which colour the fringe width is least :

1. Red
2. Green
3. Blue
4. Yellow
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Question 19: difficult

White light is used to illuminate the two silts in a Young’s double slit experiment. The separation between the slits is b and the screen is at a distance d (> > b) from the slits. At a point on the screen directly in front of one of the slits, certain wavelengths are missing. Some of these missing wavelengths are :

1. \[\lambda=\frac{b^{2}}{d}\]
2. \[\lambda=\frac{2b^{2}}{d}\]
3. \[\lambda=\frac{3b^{2}}{d}\]
4. \[\lambda=\frac{2b^{2}}{3d}\]
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