THIN LENS FORMULA FOR CONCAVE LENS
FOR CONCAVE LENS
Consider an object placed in front of a concave lens of focal length " f " on the
principle axis of the lens. Concave lens forms a virtual and erect image at a
distance of " q " from the optical centre of the lens as shown in the diagram below.
Consider similar triangles and
Similarly in similar triangles and
.............
Comparing equation (1) and (2)
p (f - q) = fq
pf - pq = fq
Dividing both sides by "pqf"
1/f - 1/p = 1/q