1. | \(-3\hat i+4\hat j+2\hat k\) | 2. | \(3\hat i-4\hat j-2\hat k\) |
3. | \(-3\hat i-4\hat j+2\hat k\) | 4. | \(-3\hat i+4\hat j-2\hat k\) |
A rod of length \(10~\text{cm}\) lies along the principal axis of a concave mirror of focal length \(10~\text{cm}\) in such a way that its end closer to the pole is \(20~\text{cm}\) away from the mirror. The length of the image is:
1. \(15~\text{cm}\)
2. \(2.5~\text{cm}\)
3. \(5~\text{cm}\)
4. \(10~\text{cm}\)
1. | \(30~\text{cm}\) away from the mirror. |
2. | \(36~\text{cm}\) away from the mirror. |
3. | \(30~\text{cm}\) towards the mirror. |
4. | \(36~\text{cm}\) towards the mirror. |
Suppose that the lower half of the concave mirror’s reflecting surface in the given figure is covered with an opaque (non-reflective) material. What effect will this have on the image of an object placed in front of the mirror?
1. | the image will show only half of the object |
2. | the image will show the whole of the object |
3. | the intensity of the image will be low |
4. | both (2) and (3) |
1. | \(120^\circ\) | 2. | \(30^\circ\) |
3. | \(60^\circ\) | 4. | \(90^\circ\) |
A beam of light is incident vertically on a glass slab of thickness \(1\) cm, and refractive index \(1.5.\) A fraction \(A\) is reflected from the front surface while another fraction \(B\) enters the slab and emerges after reflection from the back surface. The time delay between them is:
1. | \(10^{-10}\) s | 2. | \(5\times 10^{-10}\) s |
3. | \(10^{-11}\) s | 4. | \(5\times 10^{-11}\) s |
1. | \(\mu_{2}=\frac{1}{3},~\mu_{3}=\frac{1}{2}\) | 2. | \(\mu_{2}=3,~\mu_{3}=\frac{3}{2}\) |
3. | \(\mu_{2}=\frac{1}{3},~\mu_{3}=\frac{2}{3}\) | 4. | \(\mu_{2}=3,~\mu_{3}=2\) |
1. | the scattering of light. |
2. | the polarisation of light. |
3. | the colour of the sun. |
4. | the colour of the sky. |