Q. No.In Young's double-slit experiment, a student observes \(8\) fringes in a certain segment of the screen when a monochromatic light of \(600\) nm wavelength is used. If the wavelength of light is changed to \(400\) nm, then the number of fringes he would observe in the same region of the screen is:
1. \(12\)
2. \(6\)
3. \(8\)
4. \(9\)
| 1. | \(60^\circ\) | 2. | \(75^\circ\) |
| 3. | \(30^\circ\) | 4. | \(45^\circ\) |
A monochromatic light of frequency \(500~\text{THz}\) is incident on the slits of Young's double slit experiment. If the distance between the slits is \(0.2~\text{mm}\) and the screen is placed at a distance \(1~\text{m}\) from the slits, the width of \(10\) fringes will be:
| 1. | \(1.5~\text{mm}\) | 2. | \(15~\text{mm}\) |
| 3. | \(30~\text{mm}\) | 4. | \(3~\text{mm}\) |
| 1. | \(\dfrac{I}{2}\) | 2. | \(\dfrac{I}{3}\) |
| 3. | \(\dfrac{3I}{4}\) | 4. | \(\dfrac{2I}{3}\) |
| 1. | angular separation of the fringes increases. |
| 2. | angular separation of the fringes decreases. |
| 3. | linear separation of the fringes increases. |
| 4. | linear separation of the fringes decreases. |
| 1. | \(120^\circ\) | 2. | \(30^\circ\) |
| 3. | \(60^\circ\) | 4. | \(90^\circ\) |
| Statement I: | If screen is moved away from the plane of slits, angular separation of the fringes remains constant. |
| Statement Ii: | If the monochromatic source is replaced by another monochromatic source of larger wavelength, the angular separation of fringes decreases. |
| 1. | Statement I is False but Statement II is True. |
| 2. | Both Statement I and Statement II are True. |
| 3. | Both Statement I and Statement II are False. |
| 4. | Statement I is True but Statement II is False. |
Two slits are made one millimetre apart and the screen is placed one metre away. What should the width of each slit be to obtain \(10\) maxima of the double-slit pattern within the central maximum of the single-slit pattern?
1. \(2~\text{mm}\)
2. \(0.2~\text{mm}\)
3. \(0.02~\text{mm}\)
4. \(20~\text{mm}\)
Consider the following statements and then mark the incorrect statement/s.
| a. | The angular separation of the fringes increases if the screen is moved towards the plane of the slits. |
| b. | The angular separation of the fringes increases if the (monochromatic) source is replaced by another (monochromatic) source of a shorter wavelength. |
| c. | The angular separation of the fringes increases if the separation between the two slits is increased. |
| d. | The sharpness of the fringes increases when the source slit is moved closer to the double-slit plane. |
1. Only b and c
2. Only a
3. Only a, b and c
4. All of the above
Unpolarised light is incident on a plane glass surface. What should be the angle of incidence so that the reflected and refracted rays are perpendicular to each other?
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