Question

The magnification produced by a plane mirror is $ + 1$ . What does this mean?

Answer 1

Hint: The magnification of a mirror is defined as the increase in size of the image of an object. To answer this question one must be aware of the nature of image formed by a plane mirror. A plane is a mirror consisting of a flat surface that reflects the light received by an object.

Complete step by step solution:
A plane mirror is a mirror that consists of a flat reflective surface. The image formed by a plane mirror is virtual and of the same size as that of the object.

The magnification of a mirror is the ratio of distance of image from the mirror and the distance of the object from the mirror.
$m = - \dfrac{v}{u}$
Here, $m$ is the magnification, $v$ is the distance of the image from the mirror and $u$ is the distance of the object from the mirror.

In the case of a plane mirror, the distance of the object from the mirror is negative. Also, the distance of the image from the mirror is equal to the distance of the object from the mirror.
$m = - \dfrac{v}{{\left( { - u} \right)}}$
Therefore, the magnification of the plane mirror is $m = + 1$ . The positive sign of magnification indicates that the image formed by a plane mirror is erect.
Therefore, the magnification of a plane mirror is $$m = + 1$$ which means that the image formed by a plane mirror is erect.

Note: We all can see that when we place our right hand in front of a plane mirror, it appears as left hand.

This process is called lateral inversion. Lateral inversion is always experienced by the image formed from a plane mirror. The focal length and radius of curvature of a plane mirror is always taken as infinity.