A ray of light is incident on an equilateral prism at an angle of incidence \(i\) such that it is incident normally on other refracting faces. Find \(i\). [Take\(\mu_{\text{glass}}=2\)]
1. \(30^{\circ}\)
2. \(45^{\circ}\)
3. \(60^{\circ}\)
4. Not possible

If a light ray is incident normally on face \(AB\) of a prism, then for no emergent ray from second face \(AC\):
\([\mu \rightarrow\) refractive index of glass of prism]

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. \(2f\)

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:

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 \(R= 15​​\text{cm}?\)