Question

Write the formula for a lens connecting image distance (v), object distance (u) and the focal length (f). How does the lens formula differ from the mirror formula?

Answer 1

Lens formula is: 

`1/v-1/u=1/f`

Now, the mirror formula is given by:

`1/v+1/u=1/f`

In both the formulas,

u = Object distance

v = Image distance

f = Focal length

In the mirror formula, a positive sign is present between the reciprocals of the image distance and object distance.

In lens formula, a negative sign is present between the reciprocals of image distance and object distance.