Q. No.Two sources are called coherent if they produce waves:
| 1. | of equal wavelength |
| 2. | of equal velocity |
| 3. | having same shape of wavefront |
| 4. | having a constant phase difference |
Two coherent sources of different intensities send waves which interfere. The ratio of maximum intensity to the minimum intensity is \(25.\) The intensities of the sources are in the ratio:
1. \(25:1\)
2. \(5:1\)
3. \(9:4\)
4. \(625:1\)
The slits in a Young's double-slit experiment have equal width and the source is placed symmetrically with respect to the slits. The intensity at the central fringe is \(I_0.\) If one of the slits is closed, the intensity at this point will be:
1. \(I_0\)
2. \(I_0/4\)
3. \(I_0/2\)
4. \(4I_0\)
1. \(4\)
2. \(2\)
3. \(5\)
4. \(2.5\)
| 1. | \(\dfrac{2d^2}{D}\) | 2. | \(\dfrac{2d^2}{3D}\) |
| 3. | \(\dfrac{d^2}{2D}\) | 4. | \(\dfrac{d^2}{6D}\) |
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. | 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. |
Two slits are made one millimetre apart and the screen is placed one meter away. What is the fringe separation when blue-green light of wavelength \(500\) nm is used?
1. \(0.5\) mm
2. \(0.3\) mm
3. \(0.05\) mm
4. \(0.03\) mm
| 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. |
Which of the following sources gives the best monochromatic light?
1. a candle
2. a bulb
3. a mercury tube
4. a laser
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