Q. No.A ray is incident at an angle of incidence \(i\) on one surface of a small angle prism ( with angle of prism \(A\)) and emerges normally from the opposite surface. If the refractive index of the material of the prism is \(\mu,\) then the angle of incidence is nearly equal to:
1.
\(\frac{2A}{\mu}\)
2.
\(\mu A\)
3.
\(\frac{\mu A}{2}\)
4.
\(\frac{A}{2\mu}\)
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. |
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. | \(3f\) |
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. | \(\frac{3}{\sqrt{2}}\times10^{8}~\text{m/s}\) |
| 3. | \(\sqrt{2}\times10^{8}~\text{m/s}\) | 4. | \(3\times10^{8}~\text{m/s}\) |
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. \( \frac{4}{3} \)
2. \( \frac{9}{8} \)
3. \( \frac{5}{3} \)
4. \( \frac{3}{2}\)
A double convex lens has a focal length of \(25\) cm. The radius of curvature of one of the surfaces is double of the other. What would be the radii if the refractive index of the material of the lens is \(1.5?\)
| 1. | \(100\) cm, \(50\) cm |
| 2. | \(25\) cm, \(50\) cm |
| 3. | \(18.75\) cm, \(37.5\) cm |
| 4. | \(50\) cm, \(100\) cm |
A biconvex lens has power \(P.\) It is cut into two symmetrical halves by a plane containing the principal axis. The power of one part will be:
1. \(0\)
2. \(\frac{P}{2}\)
3. \(\frac{P}{4}\)
4. \(P\)
For the angle of minimum deviation of a prism to be equal to its refracting angle, the prism must be made of a material whose refractive index:
| 1. | lies between \(2\) and \(\sqrt{2}\) |
| 2. | is less than \(1\) |
| 3. | is greater than \(2\) |
| 4. | lies between \(\sqrt{2}\) and \(1\) |
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. \(10~\text{cm}\)
A thin prism of angle \(15^\circ\) made of glass of refractive index \(\mu_1=1.5\) is combined with another prism of the glass of refractive index \(\mu_1=1.75.\) The combination of the prism produced dispersion without deviation. The angle of the second prism should be:
1. \(5^\circ\)
2. \(7^\circ\)
3. \(10^\circ\)
4. \(12^\circ\)
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