The distance between the object and its real image formed by a concave mirror is minimum when the distance of the object from the centre of curvature of the mirror is: [f $\to$ focal length of the mirror]
1.  Zero
2.  $\frac{\mathrm{f}}{2}$
3.  f
4.  2f

Two slabs P & Q of transparent materials have a thickness in the ratio 2 : 5. If a ray of light takes the same amount of time to move from A to B and B to C, then the refractive index of Q with respect to P will be:

1. 0.4 

2. 2.5

3. 1.4

4. 1.85

In the following diagram, what is the distance x if the radius of curvature is R = 15 cm?

1. 30 cm

2. 20 cm

3. 15 cm 

4. 10 cm 

In the diagram shown below, the image of the point object O is formed at \(l\) by the convex lens of focal length 20 cm, where \(F_1\) and \(F_2\) are foci of the lens. The value of \(x'\) is:
        

If the space between two convex lenses of glass in the combination shown in the figure below is filled with water, then:
          

Focal lengths of objective and eyepiece of a compound microscope are 2 cm and 6.25 cm respectively. An object AB is placed at a distance of 2.5 cm from the objective which forms the image A'B' as shown in the figure. Maximum magnifying power in this case, will be:
       

A concave lens of focal length 25 cm produces an image $\frac{1}{10}\mathrm{th}$ the size of the object. The distance of the object from the lens is:

1. 225 cm

2. 250 cm 

3. 150 cm 

4. 175 cm

A mark on the surface of sphere (µ = 3/2) is viewed from a diametrically opposite position. It appears to be at a distance \(15~\mathrm{cm}\) from its actual position. The radius of sphere is:
1. 15 cm
2. 5 cm
3. 7.5 cm
4. 2.5 cm

Choose the correct mirror image of the figure:
    

1.		2.
3.		4.

A lens forms an image of a point object placed at distance 20 cm from it. The image is formed just in front of the object at a distance 4 cm from the object (and towards the lens). The power of the lens is:

1.  $-$2.25 D

2.  1.75 D

3.  $-$1.25 D

4.  1.4 D