Q. No.The power of a biconvex lens is \(10\) dioptre and the radius of curvature of each surface is \(10\) cm. The refractive index of the material of the lens is:
1.
\( \dfrac{4}{3} \)
2.
\( \dfrac{9}{8} \)
3.
\( \dfrac{5}{3} \)
4.
\( \dfrac{3}{2}\)
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. | \(3\times10^{8}~\text{m/s}\) |
An object is placed on the principal axis of a concave mirror at a distance of \(1.5f\) (\(f\) is the focal length). The image will be at:
| 1. | \(-3f\) | 2. | \(1.5f\) |
| 3. | \(-1.5f\) | 4. | \(3f\) |
A plane-convex lens of unknown material and unknown focal length is given. With the help of a spherometer, we can measure the
| 1. | focal length of the lens. |
| 2. | radius of curvature of the curved surface. |
| 3. | aperture of the lens. |
| 4. | refractive index of the material. |
Find the value of the angle of emergence from the prism given below for the incidence ray shown. The refractive index of the glass is \(\sqrt{3}\).
1. \(45^{\circ}\)
2. \(90^{\circ}\)
3. \(60^{\circ}\)
4. \(30^{\circ}\)
A lens of large focal length and large aperture is best suited as an objective of an astronomical telescope since:
| 1. | a large aperture contributes to the quality and visibility of the images. |
| 2. | a large area of the objective ensures better light-gathering power. |
| 3. | a large aperture provides a better resolution. |
| 4. | all of the above. |
A point object is placed at a distance of \(60~\text{cm}\) from a convex lens of focal length \(30~\text{cm}\). If a plane mirror were put perpendicular to the principal axis of the lens and at a distance of \(40~\text{cm}\) from it, the final image would be formed at a distance of:
| 1. | \(30~\text{cm}\) from the plane mirror, it would be a virtual image. |
| 2. | \(20~\text{cm}\) from the plane mirror, it would be a virtual image. |
| 3. | \(20~\text{cm}\) from the lens, it would be a real image. |
| 4. | \(30~\text{cm}\) from the lens, it would be a real image. |
| 1. | infinity | 2. | \(+2~\text{D}\) |
| 3. | \(+20 ~\text{D}\) | 4. | \(+5~\text{D}\) |
| 1. | \(120^\circ\) | 2. | \(30^\circ\) |
| 3. | \(60^\circ\) | 4. | \(90^\circ\) |
| 1. | \(\text{tan}^{-1}(0.750)\) | 2. | \(\text{sin}^{-1}(0.500)\) |
| 3. | \(\text{sin}^{-1}(0.750)\) | 4. | \(\text{tan}^{-1}(0.500)\) |
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