A point object is moving on the principal axis of a concave mirror of focal length \(24\) cm towards the mirror. When it is at a distance of \(60\) cm from the mirror, its velocity is \(9\) cm/sec. What is the velocity of the image at that instant?

1.	\(5\) cm/sec towards the mirror
2.	\(4\) cm/sec towards the mirror
3.	\(4\) cm/sec away from the mirror
4.	\(9\) cm/sec away from the mirror

A concave mirror is placed on a horizontal table with its axis directed vertically upwards. Let O be the pole of the mirror and C is its centre of curvature. A point object is placed at C. It has a real image, also located at C. If the mirror is now filled with water, the image will be :

1. Real, and will remain at C

2. Real, and located at a point between C and $\infty$

3. Virtual and located at a point between C and O

4. Real, and located at a point between C and O

A room (cubical) is made of mirrors. An insect is moving along the diagonal on the floor

such that the velocity of image of insect on two adjacent wall mirrors is $10 cm{s}^{-1}$. The

velocity of image of insect in ceiling mirror is

1. 10 $cm{s}^{-1}$                           

2. 20 $cm{s}^{-1}$

3. $\frac{10}{\sqrt{2}}cm{s}^{-1}$                          

4. $10\sqrt{2}cm{s}^{-1}$

Figure shows a cubical room ABCD with the wall CD as a plane mirror. Each side of the

room is 3m. We place a camera at the midpoint of the wall AB. At what distance should

the camera be focussed to photograph an object placed at A

1. 1.5 m                                     

2. 3 m

3. 6 m                                         

4. More than 6 m

If an object moves towards a plane mirror with a speed v at an angle $\theta$ to the perpendicular to the plane of the mirror, find the relative velocity between the object and the image

1. v                                           

2. 2v

3. 2v cos $\theta$                                    

4. 2v sin $\theta$

A plane mirror is placed at the bottom of the tank containing a liquid of refractive index $\mu$. P is a small object at a height h above the mirror. An observer O vertically above P outside the liquid sees P and its image in the mirror. The apparent distance between these two will be-

1. $2\mu h$                                           

2.  $\frac{2h}{\mu }$

3. $\frac{2h}{\mu -1}$                                         

4.  $h\left(1+\frac{1}{\mu }\right)$ 

To an astronaut in a spaceship, the sky appears:

1. Black                   

2. White

3. Green                 

4. Blue

A thin prism having refracting angle ${10}^{°}$ is made of glass of refractive index 1.42. This prism is combined with another thin prism of glass of refractive index 1.7. This combination produces dispersion without deviation. The refracting angle of second prism should be 

1. $4^{°}$

2. $6^{°}$

3. $8^{°}$

4. ${10}^{°}$

A beam of light from a source L is incident normally on a plane mirror fixed at a certain distance x from the source. The beam is reflected back as a spot on a scale placed just above the source L. When the mirror is rotated through a small angle $\theta$, the spot of light is found to move through a distance y on the scale. The angle $\theta$ is given by 

1. $\frac{y}{2x}$

2. $\frac{y}{x}$

3. $\frac{x}{2y}$

4. $\frac{x}{y}$

An air bubble in a glass slab with refractive index 1.5 (near normal incidence) is 5 cm deep when viewed from one surface and  3 cm deep when viewed from the opposite face. The thickness (in cm) of the slab is

1. 8           

2. 10

3. 12         

4. 16