Question

calculate the distance at which an object should be placed infront of a concave lens lens of focal length 30 cm to obtain an image of half of its size

Answer 1

Answer:

m = v/u

m = 1/2

v = u/2

Mirror Formula

1/v -1/u = 1/f

1/u = 1/f

u = f

u = -30cm

focal length Concave lens is negative