Question

the object is placed at 10cm from the optical centre of the lens having focal length 12cm find the image distance​

Answer 1

Case I : Convex lens

u = - 10cm

f = 12cm

v = ?

$v = \frac{uf}{u - f}$

$v = \frac{ - 10 \times 12}{ - 10 - 12}$

v = 5.45 cm

Case II : Concave lens

u = 10cm

f = 12cm

v = ?

$v = \frac{uf}{u - f}$

so v = -60cm