A point source of light B is placed at a distance L in front of the centre of a mirror of width d hung vertically on a wall. A man walks in front of the mirror along a line parallel to the mirror at a distance 2L from it as shown. The greatest distance over which he can see the image of the light source in the mirror is:
                       
1. d/2                                     

2. d

3. 2d                                       

4. 3d

The focal length of the objective lens and the eye lens is 4 mm and 25 mm respectively in a compound microscope. The distance between objective and eyepiece lens is 16 cm. Find its magnifying power for relaxed eye position:

A medium shows relation between i and r as shown. If the speed of light in the medium is nc then the value of n is:

1. 1.5

2. 2

3. 2^–1

4. 3^–1/2

In an astronomical telescope in normal adjustment a straight black line of length \(L\) is drawn on inside part of the objective lens. The eye-piece forms a real image of this line. The length of this image is \(l\). The magnification of the telescope is:
1. \(\frac{L}{l+1}\)
2. \(\frac{L}{l-1}\)
3. \(\frac{L+1}{L-1}\)
4. \(\frac{L}{l}\)

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:

A converging beam of rays is incident on a diverging lens. Having passed through the lens the rays intersect at a point \(15~\mathrm{cm}\) from the lens on the opposite side. If the lens is removed the point where the rays meet will move 5 cm closer to the lens. The focal length of the lens is:

The speed of light in media ${\mathrm{M}}_1$ and ${\mathrm{M}}_2$ is $1.5\times {10}^8$ $\mathrm{m}/\mathrm{s}$ and $2.0\times {10}^8$ $\mathrm{m}/\mathrm{s}$ respectively. A ray of light enters from medium ${\mathrm{M}}_1$ to ${\mathrm{M}}_2$ at an incidence angle i. If the ray suffers total internal reflection, the value of i is:

A boy is trying to start a fire by focusing sunlight on a piece of paper using an equiconvex lens of focal length 10 cm. The diameter of the sun is \(1.39\times 10^9~\text{m}\) and its mean distance from the earth is $1.5\times {10}^{11}$ $m$. What is the diameter of the sun's image on the paper?
1. \( 9.2 \times 10^{-4} \mathrm{~m} \)
2. \(6.5 \times 10^{-4} \mathrm{~m} \)
3. \(6.5 \times 10^{-5} \mathrm{~m} \)
4. \( 12.4 \times 10^{-4} \mathrm{~m}\)

Two convex lenses of focal lengths 10 cm and 30 cm are kept at a separation of 20 cm. Then the correct statement is:

A microscope has an objective of focal length 1.5 cm and an eye–piece of focal length 2.5 cm. If the distance between objective and eye-piece is 25 cm, what is the approximate value of magnification produced for relaxed eye?