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

    

1.	\(30​​\text{cm}\)	2.	\(20​​\text{cm}\)
3.	\(15​​\text{cm}\)	4.	\(10​​\text{cm}\)

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:
        

A glass slab is placed with the right-angled prism as shown in the figure. The possible value of \(\theta\) such that light incident normally on the prism does not pass through the glass slab is:

A graph is plotted between the angle of deviation \(\delta\) in a triangular prism and the angle of incidence as shown in the figure. Refracting angle of the prism is:

Three identical thin convex lenses are kept as shown in the figure. A ray passing through the lens is shown. The focal length of each lens is:

     
1. \(2\)
2. \(1.5\)
3. \(1.75\)
4. \(1.3\)

An astronomical telescope has angular magnification of \(20\) in its normal adjustment. Focal length of eyepiece is \(4\) cm. Distance between objective and eyepiece 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: