## Sign Convention for Spherical Mirror:

1:-All the distance are measured from pole of the mirror as origin.

2:-Distance measured in the same direction as that of incident light are taken as positive.

3:-Distance measured against the direction of incident light are taken as negative.

4:-Distance measured upward and perpendicular to the principal axis are taken as positive.

5:-Distance measured downward and perpendicular to the principal axis are taken as negative

## Mirror Formula:-

so

**Where**

v=distance of image from mirror

u=distance of object from mirror

f=focal length of the mirror

### Linear Magnification(m):-

The ratio of the height of image to the height of object is known as linear magnification.**Note:**

**1:- ho**always will be positive

**2:-**If

**h**i is virtual than it will be positive and

**hi**is real than it will be negative

**3:-**If the magnification has a minus sign, therefore image is real and inverted.

**4:**-If the magnification has a positive sign, therefore image is virtual and erect.