1. [2081 GIE ‘B’] The wavelength of the two waves is shown in the figure is 15cm each. What is the phase difference between those waves at X?

1. [latex]\pi[/latex]
2. [latex]0.1\pi[/latex]
3. [latex]0.67\pi[/latex]
4. [latex]3.5\pi[/latex]

2. [2079 GIE ‘A’] In Young’s double slits experiment, the distance between the slits is halved and distance between slits and screen is doubled. Then, fringe width becomes.

1. Half
2. Double
3. Four times
4. Six times

New Course

1. [2082] Prove that bright and dark fringes are equally spaced in Young’s double slit experiment. [3]
2. [2081 GIE ‘A’] In a Young’s double slit experiment, in which conditions will you get constructive and destructive interference? Explain on the basis of path difference. [2]
3. [2081 GIE ‘B’]

1. What is interference of light? [1]
2. Write suitable conditions for interference. [2]
3. What changes in the interference pattern observed in Young’s double slit experiment when

1. light of smaller frequency is used. [1]
2. the apparatus is immersed in water. [1]

4. [2081 B/C] What is interference of light? Two coherent waves, each of intensity I, are producing an interference pattern. What will be the resultant intensity at a point of

1. constructive interference and            
2. destructive interference? [3]

5. [2081 ‘D’]

1. Does interference of light follow the principle of conservation of energy? Justify. [1]            
2. Obtain the expression for the position of n^th order maxima from central bright fringe in Young’s double slit experiment. [2]

6. [2080 GIE ‘A’]

1. Two narrow slits are illuminated by a single monochromatic source of light. Name the pattern obtained on the screen and explain how these patterns are obtained. [1]
2. One of these slits is now completely covered. Name the pattern obtained on the screen. [1]
3. Write the difference between the patterns obtained in the above two cases on the basis of Huygen’s principle. [1]

7. [2080 ‘P’] In Young’s double slit experiment, what changes will you observe in fringe width for the following operations:

1. When experiment is shifted from air to inside water. [1]
2. When slits width is increased? [1]

8. [2080 R] In Young’s double slit experiment, bright and dark bands are formed on a screen due to interference of light.

1. Define interference of light. [1]
2. Calculate the fringe width ([latex]\beta[/latex]). [3]
3. When the whole apparatus is immersed in a liquid, what will be the effect on the fringe width? [2]

9. [2079 GIE ‘B’]

1. Define interference of light. Does it follow the principle of conservation of light energy? Justify your answer. [2]
2. In Young’s double slit experiment, show that bright and dark fringes are equally spaced. [3]

10. [2079 ‘O’]

1. Write sustainable conditions for interference? [2]            
2. “The bright and dark fringes are equally spaced.” Justify this statement from Young’s double slit experiment. [3]

11. [2079 V] The diagram represents the experimental arrangement used to produce interference fringes in Young’s double slit experiment.

1. What are coherent sources of light?                           [1]
2. What do you mean by interference of light?          [1]
3. In the above experiment, if the slits S₁ & S₂ are illuminated by a monochromatic source of light of wavelength [latex]\lambda[/latex], show that the width of bright fringe is equal to width of dark fringe as given by [latex]\beta = \frac{\lambda D}{d}[/latex]. [4]
4. If the distance between slits and the screen is doubled and slits separation is halved, what will be the effect on fringe width? [1]
5. What happened to fringe width if whole apparatus is immersed in water? [1]

Old Course

SHORT ANSWER QUESTION

12. [2075 ‘S’] What happens on the interference fringes in a Young’s double slit experiment when (i) the screen is moved away (ii) the source is replaced by another source of shorter wavelength?
13. [2074 ‘B’] What are coherent sources of light? can two different bulbs, similar in all respects, act as coherent sources?
14. [2073 ‘C’] Two waves are represented in usual notation as y₁ = a₁sin[latex]\omega t[/latex]  and y₂ = a₂ cos[latex]\omega t[/latex]. Their intensities are I₁ and I₂. What would be the ratio of their amplitudes when I₁ = 2I₂?
15. [2072 ‘S’] A two – slit interference experiment is setup and the fringes are displaced on a screen. Then the whole apparatus is immersed in a water. How does the fringe pattern change?
16. [2072 ‘D’] Does the interference of light waves obey the laws of conservation of energy? Explain.

LONG ANSWER QUESTION

17. [2078 ‘C’] Describe Young’s double slit experiment and derive an expression for the fringe width in the interference pattern.
18. [2076 GIE ‘B’] Discuss Young’s double slit experiment and show that bright and dark fringes are of equal width.
19. [2075 ‘A’, 2074 ‘A’] Define coherent sources of light. prove that the dark and bright fringes are equally spaced in Young’s double slit experiment.
20. [2074 ‘S’] Describe Young’s double slit experiment and derive an expression for the fringe width.

OR [2073 ‘S’] Prove analytically that the bright and dark fringes in Young’s double slit experiment are equally spaced.

OR [2073 ‘C’] What are coherent sources of light? Describe double slit experiment to find the fringe width from the experiment performed with light waves.

OR [2072 ‘S’] What are the conditions for constructive and destructive interference of light waves? Show that in Young’s double slit experiment the dark and bright fringes are equally spaced.

OR [2072 ‘C’] What are coherent sources? Derive an expression for the fringe width in Young’s double slit experiment.

New Course

1. [2081 GIE ‘A’] In Young’s slit experiment, the separation of the first to fifth fringes is 2.5 mm when the wavelength used is 620 nm. The distance from the slits to the screen is 80 cm. Calculate the separation of two slits. [3] Ans: [latex]7.9\times 10^{-4}[/latex] m
2. [2079 GIE ‘B’] In Young’s double slit experiment the slits are 0.03 cm apart and the screen is placed 1.5m away. The distance between the central bright fringe and fourth fringe is 1 cm. Calculate the wave length of light used. [3] Ans: [latex]5\times 10^{-7}[/latex] m
3. [2079 ‘O’] In a Young’s slits experiment, the separation of first to fifth fringes is 2.5 mm when the wave length used is 620 nm. The distance from the slits to the screen is 80 cm. Calculate the separation of two slits. Ans: [latex] 7.94\times 10^{-4}[/latex] m
4. [2076 GIE ‘A’] In a Young’s experiment two slits spaced 0.45 mm apart are placed 75 cm from a screen. What is the distance between second and third dark lines in the interference pattern on a screen when slits are illuminated with light of 500 nm? Ans: 8.33 x 10^-4 m
5. [2076 ‘B’, 2074 ‘B’] In a Young’s double slit experiment, the separation of four bright fringes is 2.5 mm. The wavelength of light used is 6.2 x 10^-5 cm and the distance from the slits to the screen is 80 cm. Calculate the separation of slits. Ans: [latex]5.9\times 10^{-4}[/latex] m
6. [2075 ‘S’] The distance between two coherent sources in Young’s double slit experiment is 0.3 mm and the interference pattern is observed on a screen 60 cm from the sources. If the wavelength of light used is 6 x 10^-7 m, calculate the fringe width of the interference pattern. Ans: 1.2 x 10^-3 m
7. [2073 ‘D’] The separation between the consecutive dark fringes in a Young’s double slit experiment is 1 mm. The screen is placed at a distance of 2 m from the slits of 1.0 mm separation. What is the wavelength of light used in the experiment? Ans: 5 x 10^-7 m
8. [2072 ‘D’] In Young’s double slit experiment, the slits are 0.03 cm apart and the screen is placed 1.5 m away. The distance between the central bright fringe and fourth bright fringe is 1 cm. Calculate the wavelength of light used. Ans: [latex]5\times 10^{-7}[/latex] m
9. [2072 ‘E’] Two coherent sources A and B of radio waves are 5 m apart. Each source emits waves with wavelength 6m. Consider points along the line between two sources, at what distances, if any, from A is the interference constructive? Ans: 2.5 m
10. In a two-slit interference experiment, the slits are 0.200 mm apart, and the screen is at a distance of 1.00 m. The third bright fringe is found at 9.49 mm from the central fringe. Find the wavelength of the light used. Ans: [latex]6.33\times 10^{-7}[/latex] m
11. In an experiment using Young’s slits the distance between the centre of the interference pattern and the tenth bright fringe on either side is 3.44 cm. Distance between the slits and the screen is 2.0 m. If the wavelength of light used is [latex]5.89\times 10^{-7}[/latex] m, determine the slit separation and the angle made by the central bright fringe at the slit. Ans: [latex]3.42\times 10^{-4}[/latex] m, [latex]1.72\times 10^{-3}[/latex] radian
12. Two slits are 0.3 mm apart and placed 50 cm from a screen. What is the distance between the second and third dark lines of the interference pattern when the slits are illuminated with a light of 600 nm wavelengths? Ans: [latex]1\times 10^{-3}[/latex] m