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. \(2f\)

A point object \(O\) is placed at a distance \(20\) cm from a biconvex lens of the radius of curvature \(20\) cm and \(\mu=1.5.\) The final image produced by lens and mirror combination will be at:

A person can see objects clearly between 1 m and 3 m. The power of lens required to correct near point will be:

1.  $-$2.5 D

2.  + 3 D

3.  + 1.5 D

4.  $-$1.75 D

In the case of a compound microscope, the image formed by the objective lens is:

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:
        

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: