Write the spherical mirror formula and explain the meaning of each symbol used in it.

The spherical mirror formula is the relation among the image distance ,object distance and focal length of the mirror .

If The image distance is = v

The object distance is = u

The focal length of mirror =f

Then the mirror formula will be –

The sign convention can be used as given in the figure –

We can see following things from the figure –

• Focal length (f) is positive for a convex lens and convex mirror.

• Focal length(f) is negative for concave lens and concave mirror.

• Image distance (v) can be both positive and negative for convex lens and concave mirror depending on the position of the object.

• Image distance(v) is always negative for a concave lens.

• Image distance(v) is always positive for a convex mirror.

• Object distance (u) is negative for convex as well as the concave mirror.