Question

Q. Using mirror formula show that

In the plane mirror both object and image distance are the same and image is virtual and erect

Answer 1

From the mirror formula

We know,

$\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$

The object distance is the negative and the focal length for the plane mirror is infinity

So we can write,

$\frac{1}{v}-\frac{1}{u}=\frac{1}{\infty }$

Or,

$\frac{1}{v}-\frac{1}{u}=0$

$Or,\frac{1}{v}=\frac{1}{u}$

Therefore, v = u

From the above, we can conclude that for the plane mirror object distance is always equal to the image distance.