In a glass \((\mu = 1.5)\) sphere with a radius of \(10​​\text{cm},\) there is an air bubble \(B\) at a distance of \(5​​\text{cm}\) from \(C.\) The distance of the bubble from the surface of the sphere (i.e., point \(A\)) as observed from the point \(P\) in the air will be:

            

1.	\(4.5​​\text{cm}\)	2.	\(20.0​​\text{cm}\)
3.	\(9.37​​\text{cm}\)	4.	\(6.67​​\text{cm}\)

A lens forms an image of a point object placed at distance \(20~\text{cm}\) from it. The image is formed just in front of the object at a distance \(4~\text{cm}\) from the object (and towards the lens). The power of the lens is:
1. \(-2.25~\text D\) 
2. \(1.75~\text D\) 
3. \(-1.25~\text D\) 
4. \(1.4~\text D\) 

The distance between the object and its real image formed by a concave mirror is minimum when the distance of the object from the center of curvature of the mirror is: (where\(f\) is the focal length of the mirror)
1. zero
2. \(\dfrac{f}{2}\)
3. \(f\)
4. \(2f\)

In the following diagram, what is the distance \(x\) if the radius of curvature is \(R= 15​​\text{cm}?\)

In the diagram shown below, the image of the point object \(O\) is formed at \(l\) by the convex lens of focal length \(20~\text{cm},\)  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:
               

The focal lengths of the objective and eyepiece of a compound microscope are \(2​​\text{cm}\) and \(6.25​​\text{cm}\) respectively. An object \(AB\) is placed at a distance of \(2.5​​\text{cm}\) from the objective which forms the image \(A'B'\) as shown in the figure. The maximum magnifying power in this case, will be:
          

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

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