Q. No.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. \(45^{\circ}\)
3. \(60^{\circ}\)
4. Not possible
| 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
The distance between the object and its real image formed by a concave mirror is minimum when the distance of the object from the centre of curvature of the mirror is: [\(f\rightarrow\) focal length of the mirror]
| 1. | Zero | 2. | \(\dfrac{f}{2}\) |
| 3. | \(f\) | 4. | \(2f\) |
A point object \(O\) is placed at a distance \(20\) cm from a biconvex lens of the radius of curvature \(20\) cm and \(\mu=1.5.\) The final image produced by lens and mirror combination will be at:
| 1. | \(10\) cm from the mirror |
| 2. | \(20\) cm from the lens |
| 3. | \(-20\) cm from the lens |
| 4. | \(-15\) cm from the mirror |
A person can see objects clearly between 1 m and 3 m. The power of lens required to correct near point will be:
1. 2.5 D
2. + 3 D
3. + 1.5 D
4. 1.75 D
In the case of a compound microscope, the image formed by the objective lens is:
| 1. | Virtual, erect, and diminished. |
| 2. | Real, erect, and magnified. |
| 3. | Virtual, inverted, and enlarged. |
| 4. | Real, inverted, and enlarged. |
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