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 $\theta$

To an astronaut in a spaceship, the sky appears:

1. Black                   

2. White

3. Green                 

4. Blue

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. $\frac{x}{y}$

Two identical glass $\left({\mu }_g=3/2\right)$ equi-convex lenses of focal length $f$ each are kept in contact. The space between the two lenses is filled with water $\left({\mu }_w=4/3\right)$. The focal length of the combination is

1.  $f/3$             
2. $f$
3. $\frac{4f}{3}$               
4. $\frac{3f}{4}$

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

An astronomical telescope has an objective and eyepiece of focal lengths 40 cm and 4 cm respectively. To view an object 200 cm away from the objective, the lenses must be separated by a distance of :
1. 46.0 cm

2. 50.0 cm  

3. 54.0 cm

4. 37.3 cm 

Match the corresponding entries of Column 1 with Column 2. [Where m is the magnification produced by the mirror]

Column 1                         Column 2 
A. m=-2                     a. Convex mirror   
B. m=-1/2                  b. Concave mirror
C. m=+2                    c. Real image
D. m=+1/2                 d. Virtual Image

1. A->a and c;B->a and d; C->a and b; D->c and d

2. A->a and d; B->b and c; C->b and d; D-> b and c

3. A->c and d; B->b and d;C->b and c;D->a and d

4. A->b and c; B->b and c; C->b and d; D->a and d

The angle of incidence for a ray of light at a refracting surface of a prism is 45°. The angle of prism is 60°. If the ray suffers minimum deviation through the prism, the angle of deviation and refracting index of the material of the prism respectively are

(a)30°,$\sqrt{2}$

(b)45°,$\sqrt{2}$

(c)30°,$\frac{1}{\sqrt{2}}$

(d)45°,$\frac{1}{\sqrt{2}}$