A convex lens of power 0.04 dioptre produces an image which is double the size of object placed in front of it. Find the position of the object.

Explanation

Data supplied,
P = 0.04 dioptre, `" " ` m = 2, u = ?
`f = (1)/(p) = (1)/(0.04) = (100)/(4) = 2.5 ` m
` m = (f)/(u + f) 2 =(25)/(u + 25) 2u + 50 = 25 2u = - 25 u = - 12.5 m `