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) |
The near point of a hypermetropic person is \(75\) cm from the eye. What is the power of the lens required to enable the person to read clearly a book held at \(25\) cm from the eye?
1. \(+2.67\) D
2. \(-1.25\) D
3. \(-2.67\) D
4. \(+1.25\) D
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. \(10~\text{cm}\)
To increase the angular magnification of a simple microscope, one should increase:
1. | the focal length of the lens | 2. | the power of the lens |
3. | the aperture of the lens | 4. | the object size |
If the critical angle for total internal reflection from a medium to vacuum is \(45^{\circ}\), the velocity of light in the medium is:
1. | \(1.5\times10^{8}~\text{m/s}\) | 2. | \(\dfrac{3}{\sqrt{2}}\times10^{8}~\text{m/s}\) |
3. | \(\sqrt{2}\times10^{8}~\text{m/s}\) | 4. | \(3\times10^{8}~\text{m/s}\) |
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. | \(30\) cm | 2. | \(60\) cm |
3. | \(\dfrac{20}3\) cm | 4. | \(\dfrac{40}{3}\) cm |