Question

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

Answer 1

Formula for a lens connecting image distance (v), object distance (u) and the focal length (f) id :

1/v - 1/u =  /1f

This is the lens formula.

The lens formula has a minus sign(-) between 1/v and 1/u whereas the mirror formula has a plus sign(+) between 1/v and 1/u.

Mirror formula :

1/v + 1/u = 1/f