1. | \(10\) cm | 2. | \(15\) cm |
3. | \(20\) cm | 4. | \(25\) cm |
A concave lens forms the image of an object such that the distance between the object and image is \(10\) cm. If magnification of the image is \(\frac{1}{4},\) the focal length of the lens is:
1. \(-\frac{20}{3}~\text{cm}\)
2. \(\frac{20}{3}~\text{cm}\)
3. \(\frac{40}{9}~\text{cm}\)
4. \(-\frac{40}{9}~\text{cm}\)
A ray of light incident on a prism of angle \(A\) and refractive index \(\mu\) will not emerge out of the prism for any angle of incidence, if:
1. \(\mu>\sin \frac{A}{2}\)
2. \(\mu>\cos{A}\)
3. \(\mu<\frac{1}{\sin A}\)
4. \(\mu>\frac{1}{\sin \frac{A}{2}}\)
In normal adjustment, the angular magnification of an astronomical telescope is \(39\). If length of the tube is \(2\) m, then focal length of the objective and eyepiece are respectively:
1. | \(195~\text{cm}, 5~\text{cm}\) | 2. | \(190~\text{cm}, 10~\text{cm}\) |
3. | \(20~\text{cm}, 180~\text{cm}\) | 4. | \(10~\text{cm}, 190~\text{cm}\) |
1. | \(30^\circ\) | 2. | \(37^\circ\) |
3. | \(53^\circ\) | 4. | \(45^\circ\) |
If a light ray is incident normally on face \(AB\) of a prism, then for no emergent ray from second face \(AC\):
\([\mu \rightarrow\) refractive index of glass of prism]
1. | \(\mu=\frac{2}{\sqrt{3}}\) | 2. | \(\mu>\frac{2}{\sqrt{3}}\) |
3. | \(\mu<\frac{2}{\sqrt{3}}\) | 4. | \(\mu\) can have any value. |
1. | \(4.5\) cm | 2. | \(20.0\) cm |
3. | \(9.37\) cm | 4. | \(6.67\) cm |
A lens forms an image of a point object placed at distance \(20\) cm from it. The image is formed just in front of the object at a distance \(4\) cm from the object (and towards the lens). The power of the lens is:
1. \(-2.25\) D
2. \(1.75\) D
3. \(-1.25\) D
4. \(1.4\) D