A tall man, of height 6 feet, wants to see his full image. The required minimum length of the mirror will be:

1. 12 feet

2. 3 feet

3. 6 feet

4. Any length

A beam of light composed of red and green rays is incident obliquely at a point on the face of a rectangular glass slab. When coming out on the opposite parallel face, the red and green rays emerge from:

The refractive index of the material of a prism is $\sqrt{2}$ and its refracting angle is 30º. One of the refracting surfaces of the prism is made a mirror inwards. A beam of monochromatic light entering the prism from the other face will retrace its path after reflection from the mirrored surface if its angle of incidence on the prism is:

1. 60º

2. 0º

3. 30º

4. 45º 

For the given incident ray as shown in the figure, in the condition of total internal reflection of this ray, the minimum refractive index of the prism will be:

1. $\frac{\sqrt{3}+1}{2}$

2. $\frac{\sqrt{2}+1}{2}$

3. $\sqrt{\frac{3}{2}}$

4. $\sqrt{\frac{7}{6}}$

A bulb is located on a wall. Its image is to be obtained on a parallel wall with the help of a convex lens. If the distance between parallel walls is 'd' then the required focal length of the lens placed in between the walls is:

1. Only $\frac{\mathrm{d}}{4}$

2. Only $\frac{\mathrm{d}}{2}$

3. More than $\frac{\mathrm{d}}{4}$ but less than $\frac{\mathrm{d}}{2}$

4. Less than or equal to $\frac{\mathrm{d}}{4}$

In a compound microscope, the magnification is 95, the distance of the object from the objective lens is 1/3.8 cm and the focal length of the objective is 1/4 cm. What is the magnification of the eyepiece when the final image is formed at the least distance of distinct vision?
1. 5
2. 10
3. 100
4. None

A convex lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens. Then its focal length will:

1. become zero.

2. become infinite.

3. become small, but non-zero.

4. remain unchanged.

A biconvex lens is cut into two halves along (i) XOX' and (ii) YOY' as shown in the figure. Let f, f' f" be the focal lengths of the complete lens, of each half in case (i), and of each half in case (ii), respectively.
   
Choose the correct statement from the following:

1. f' = f, f" = 2f

2. f' = 2f, f" = f

3. f' = f, f" = f

4. f' = 2f, f" = 2f

Light enters at an angle of incidence in a transparent rod of refractive index n. For what value of the refractive index of the material of the rod, will the light, once entered into it, not leave it through its lateral face whatsoever be the value of angle of incidence?
1. $n >\sqrt{2}$
2. 1.0
3. 1.3
4. 1.4

A plane convex lens (µ = 1.5) has a radius of curvature 10 cm. It is silvered on its plane surface. The focal length of the lens after silvering is:

1. 10 cm

2. 20 cm

3. 15 cm

4. 25 cm