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. | \(\dfrac{3}{\sqrt{2}}\times10^{8}~\text{m/s}\) |
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. | \( \dfrac{4}{3} \) | 2. | \( \dfrac{9}{8} \) |
3. | \( \dfrac{5}{3} \) | 4. | \( \dfrac{3}{2}\) |
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. | \(2\) and \(\sqrt{2}\) | lies between
2. | \(1\) | is less than
3. | \(2\) | is greater than
4. | \(\sqrt{2}\) and \(1\) | lies between
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. \(12^\circ\)
A converging beam of rays is incident on a diverging lens. Having passed through the lens the rays intersect at a point \(15~\text{cm}\) from the lens on the opposite side. If the lens is removed the point where the rays meet will move \(5~\text{cm}\) closer to the lens. The focal length of the lens is:
1. \(5~\text{cm}\)
2. \(-10~\text{cm}\)
3. \(20~\text{cm}\)
4. \(-30~\text{cm}\)
The speed of light in media \(M_1\) and \(M_2\) is \(1.5\times10^{8}\) m/s and \(2.0\times10^{8}\) m/s respectively. A ray of light enters from medium \(M_1\) and \(M_2\) at an incidence angle \(i.\) If the ray suffers total internal reflection, the value of \(i\) is:
1. | equal to or less than \(\text{sin}^{-1}\left (\frac{3}{5} \right )\) |
2. | equal to or greater than \(\text{sin}^{-1}\left (\frac{3}{4} \right )\) |
3. | less than \(\text{sin}^{-1}\left (\frac{2}{3} \right )\) |
4. | equal to \(\text{sin}^{-1}\left (\frac{2}{3} \right )\) |
A ray of light is incident on a \(60^\circ\) prism at the minimum deviation position. The angle of refraction at the first face (i.e. incident face) of the prism is:
1. \(30^\circ\)
2. \(45^\circ\)
3. \(60^\circ\)
4. zero