A ray of light falls on a prism \(ABC\) \((AB= BC)\) and travels as shown in figure. The refractive index of the prism material should be greater than:

| 1. | \(4 /{3}\) | 2. | \( \sqrt{2}\) |
| 3. | \(1.5\) | 4. | \( \sqrt{3}\) |
| 1. | \(80~\text{cm}\) | 2. | \(40~\text{cm}\) |
| 3. | \(60~\text{cm}\) | 4. | \(20~\text{cm}\) |
| 1. | \(f' = f\) |
| 2. | \(f'<f\) |
| 3. | \(f'>f\) |
| 4. | The information is insufficient to predict |
| 1. | \(X+Y\) | 2. | \(\dfrac{X +Y}{2}\) |
| 3. | \(X-Y\) | 4. | \(\dfrac{X -Y}{2}\) |
A plane mirror is placed at the bottom of a fish tank filled with water of refractive index \(\dfrac{4}{3}.\) The fish is at a height \(10~\text{cm}\) above the plane mirror. An observer \(O\) is vertically above the fish outside the water. The apparent distance between the fish and its image is:

| 1. | \(15\text{cm}\) | 2. | \(30~\text{cm}\) |
| 3. | \(35~\text{cm}\) | 4. | \(45~\text{cm}\) |
If \(C_1,~C_2 ~\mathrm{and}~C_3\) are the critical angle of glass-air interface for red, violet and yellow color, then:
| 1. | \(C_3>C_2>C_1\) | 2. | \(C_1>C_2>C_3\) |
| 3. | \(C_1=C_2=C_3\) | 4. | \(C_1>C_3>C_2\) |
An object is placed \(20~\text{cm}\) in front of a concave mirror of a radius of curvature \(10~\text{cm}.\) The position of the image from the pole of the mirror is:
1. \(7.67~\text{cm}\)
2. \(6.67~\text{cm}\)
3. \(8.67~\text{cm}\)
4. \(9.67~\text{cm}\)
| 1. | \(\frac{\sqrt{3}}{2} \) | 2. | \(1.5 \) |
| 3. | \(1.732 \) | 4. | \( 2\) |
A thin rod of length \(\dfrac{f}{3}\) lies along the axis of a concave mirror of focal length \(f.\) One end of its magnified, real image touches an end of the rod. The length of the image is:
| 1. | \(f\) | 2. | \(\dfrac{f}{2}\) |
| 3. | \(2f\) | 4. | \(\dfrac{f}{4}\) |
A thin equiconvex lens of power \(P\) is cut into three parts \(A,B,\) and \(C\) as shown in the figure. If \(P_1,P_2\) and \(P_3\) are powers of the three parts respectively, then:

| 1. | \(P_1=P_2=P_3\) | 2. | \(P_1>P_2=P_3\) |
| 3. | \(P_1<P_2=P_3\) | 4. | \(P_2=P_3=2P_1\) |