Calculate Focal Length Convex Which Produces Virtual Image Distance Object Placed Front

Calculate the focal length of a convex lens which produces a virtual image at a distance of 50 cm of an object placed 20 cm in front of it.

Answers:

V = – 50 cm (Virtual image)

u = -20 cm

1/v – 1/u = 1/f

1/-50 – 1/-20 = 1/f

(-2 + 5)/100 = 1/f

3/100 = 1/f

F = 33.3 cm