An observer can see through a pinhole the top end of a thin rod of height h, placed as shown in the figure. The beaker height is 3h and its radius h. When the beaker is filled with a liquid up to a height 2h, he can see the lower end of the rod. Then the refractive index of the liquid is

                        

1. $5/2$                                   

2. $\sqrt{\left(5/2\right)}$

3. $\sqrt{\left(3/2\right)}$                               

4. 3/2

In an experiment of find the focal length of a concave mirror a graph is drawn between the magnitudes of u and v.  The graph looks like

1.		2.
3.		4.

As the position of an object \((u)\) reflected from a concave mirror is varied, the position of the image \((v)\) also varies. By letting the \(u\) change from \(0\) to infinity, the graph between \(v\) versus \(u\) will be:

1.		2.
3.		4.

A glass prism $\left(\mu =1.5\right)$ is dipped in water $\left(\mu =4/3\right)$ as shown in figure. A light ray is incident normally on the surface AB. It reaches the surface BC after totally reflected, if

1. $\sin \theta \ge \raisebox{1ex}{$ 8$}\!\left/ \!\raisebox{-1ex}{$9$}\right.$                           
2. $\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.<\sin \theta <\raisebox{1ex}{$ 8$}\!\left/ \!\raisebox{-1ex}{$9$}\right.$
3. $\sin \theta \le \raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.$                           
4. It is not possible

A convex lens A of focal length \(20~\text{cm}\) and a concave lens \(B\) of focal length \(5~\text{cm}\) are kept along the same axis with the distance \(d\) between them. If a parallel beam of light falling on \(A\) leaves \(B\) as a parallel beam, then distance \(d\) in \(\text{cm}\) will be:
1. \(25\)                         
2. \(15\) 
3. \(30\)                         
4. \(50\)

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

1. 1.5

2. 2

3. 2^–1

4. 3^–1/2

For a concave mirror, if the virtual image is formed, the graph between m and u is of the form :

1.		2.
3.		4.

For a convex lens, the distance of the object is taken on X-axis and the distance of the image is taken on Y-axis, the nature of the graph so obtained is :

1. Straight line                     

2. Circle

3. Parabola                          

4. Hyperbola

The diameter of a plano-convex lens is 6 cm and thickness at the centre is 3 mm. If the

speed of light in the material of the lens is $2\times {10}^8\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$sec$}\right.$, the focal length of the lens is

1. 15 cm                         

2. 20 cm

3. 30 cm                         

4. 10 cm