Question

Define magnification produced by a mirror and how does it help us in finding out if an image is real or virtual.

Answer 1

Hint: Magnification helps us in judging the size of the image formed in comparison to that of the object. It tells us whether the image formed is magnified, diminished ,equal to object when object is placed at different positions on the principal axis.
In the case of a mirror, real images are formed in front the mirror and virtual images are formed behind the mirror.

Complete step-by-step answer:
Magnification is the increase in the image size produced by spherical mirrors with respect to the object size. It is the ratio of the height of the image to the height of the object and is denoted as m. The magnification, m produced by a spherical mirror can be expressed as:
$m=\dfrac{{{h}^{'}}}{h}$ where ${{h}^{'}}$ is height of image and h is height of object.
It is also equal to the negative of the ratio of the image distance$\left( v \right)$ to object distance $\left( u \right)$.
$m=-\dfrac{v}{u}$
According to convention object distance is always negative. In the case of a mirror, real images are formed in front the mirror and virtual images are formed behind the mirror.
From the formula, we can see that when the magnification is positive, that means image distance is positive or the image is formed behind the mirror. So it is virtual. And when the magnification is negative, that means image distance is negative or the image is formed in front of the mirror. So it is real. In this way magnification helps us in judging images for being virtual or real.

Note: Some points to remember are,
The positive magnitude of magnification indicates virtual and erect image.
The negative magnitude of magnification indicates real and inverted image.
There are many applications of magnification of a mirror such as a precision magnifier and many more.