Q. No.A light wave can travel:
| (a) | in vacuum |
| (b) | in vacuum only |
| (c) | in a material medium |
| (d) | in a material medium only |
Choose the correct option from the options given below:
| 1. | (a) and (b) only |
| 2. | (b) and (c) only |
| 3. | (a) and (c) only |
| 4. | (c) and (d) only |
| Assertion (A): | Radio waves can be polarised. |
| Reason (R): | Sound waves in the air are longitudinal in nature. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | Both (A) and (R) are False. |
The wavefronts of a light wave travelling in vacuum are given by \(x+y+z=c\). The angle made by the direction of propagation of light with the X-axis is:
1. \(0^{\circ}\)
2. \(45^{\circ}\)
3. \(90^{\circ}\)
4. \({\cos^{-1}\left({1}/{\sqrt{3}}\right )}\)
Light waves travel in vacuum along the X-axis. Which of the following may represent the wavefronts?
1. \(x=c\)
2. \(y=c\)
3. \(z=c\)
4. \(x+y+z=c\)
When the light diverges from a point source, the shape of the wavefront is:
1. Parabolic.
2. Plane.
3. Spherical.
4. Elliptical.
For light diverging from a point source:
| (a) | the wavefront is spherical. |
| (b) | the intensity decreases in proportion to the distance squared. |
| (c) | the wavefront is parabolic. |
| (d) | the intensity at the wavefront does not depend on the distance. |
| 1. | (a), (b) | 2. | (a), (c) |
| 3. | (b), (c) | 4. | (c), (d) |
Which of the following is not true?
| 1. | The speed of light is dependent on the colour of the light. |
| 2. | The speed of violet light is less than the speed of the red light in glass. |
| 3. | The frequency of light never depends upon the property of the medium. |
| 4. | When the light diverges from a point source, the shape of the wavefront is plane. |
When the light is coming from a distant star that is intercepted by the earth, the shape of the wavefront is:
| 1. | Spherical. | 2. | Plane. |
| 3. | Elliptical. | 4. | None of these. |
The refractive index of glass is \(1.5\). What is the speed of light in glass?
1. \(2 \times 10^{8}~\text{m/s}\)
2. \(3 \times 10^{8} ~\text{m/s}\)
3. \(1.5 \times 10^{8} ~\text{m/s}\)
4. \(2.2 \times 10^{8}~\text{m/s}\)
The inverse square law of intensity (i.e., the intensity \(\propto \frac{1}{r^2})\) is valid for:
1. a point source
2. a line source
3. a plane source
4. a cylindrical source
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