Question

Magnification of a concave lens is-
(A) $ > 0$ and $ < 1$
(B) $ > 1$ or $ < - 1$
(C) $ > - 1$ and $ < 1$
(D) Insufficient information

Answer 1

Hint Magnification is defined as the ratio between the size of an image compared with the original size of the object. Magnification is also determined by the ratio of the distance of the image from the pole to the distance of the object to the pole.

Complete Step by step solution
Magnification of an object consists of two parts which tell about the nature of an image-
The sign of the magnification tells if the image formed is inverted or upright. A real image is inverted in nature, so a negative sign is used to represent a real and inverted image. A virtual image on the other hand is upright, thus it is represented by a positive sign of magnification.
The magnitude of the magnification represents the ratio of the size of the image with respect to the size of the actual object. If this value is less than one, it signifies that the image is smaller in size than the actual object or diminished, it also tells that the distance of the image formed from the pole of the lens is less than the distance between the lens and the object. If this value is more than one, it represents a larger image than the original object or enlarged image. If the magnitude is equal to one, it represents the same sized image and object.
A concave lens is also known as a diverging lens. It diverges a beam of rays directed towards it. The rays never meet in reality but the diverged rays can be traced backward to create a virtual image.
The virtual images are upright, thus the sign of the magnification caused by a concave lens would be positive.
A concave lens always forms a diminished image of the object, thus the value of magnification produced by it ranges from $0$ to $1$.
Therefore the magnification produced by a concave mirror is, $ > 0$ and $ < 1$.

Option (A) is correct.

Note A concave lens always produces diminished, virtual and upright images. A convex lens on the other hand can produce a variety of images based on the distance between the object and the optical center of the lens.