Question

A virtual, erect and diminished image is formed by a concave lens, when the object is:
(A) beyond 2 F
(B) at 2 F
(C) between F and 2F
(D) all the above

Answer 1

Hint
We can use the knowledge that a concave lens is a lens that possesses at least one surface that curves inwards. It is a diverging lens, meaning that it spreads out light rays that have been refracted through it. A concave lens is thinner at its centre than at its edges, and is used to correct short-sightedness (myopia). Concave Lenses Are for the Near-sighted, Convex for the Farsighted. Concave lenses are used in eyeglasses that correct near-sightedness. Because the distance between the eye's lens and retina in near-sighted people is longer than it should be, such people are unable to make out distant objects clearly.

Complete step by step answer
A concave lens always gives a virtual, erect and diminished image whatever may be the position of the object. The position of the images when the object is placed at infinity, between O and F and any position between infinity and O are given.
Therefore, image can be formed as virtual, erect and diminished beyond 2F, at 2F or between F and 2F. So, all of the conditions are applicable.
Therefore, the correct answer is Option (D).

Note
It is required to be sure that in actuality, there are two focal points for every lens, the same distance from the lens, on opposite sides. The distance from the lens to the focal point is called the focal length. For converging lenses, the focal length is always positive, while diverging lenses always have negative focal lengths. Plano-concave - A lens in which one side is concave and the other is plano. Plano-concave lenses are diverging lenses.
Thus, a positive meniscus is a converging lens where one side is concave and the other convex. Negative meniscus - A diverging lens where one side is concave and the other convex.