An image in a convex lens is upright and magnified 3 times. If the focal length of the lens is 15 cm, what is the object distance?
A
10 cm
B
25 cm
C
16 cm
D
14 cm
Verified Correct Answer: A.
Physical Principles & Numerical Solution
m = v/u = -3
v = -3u
f = 15cm
1/v + 1/U = 1/f
1/-3U + 1/u = 1/15
2/3u = 1/15
3U = 15 x 2
U = 30/3
= 10 cm
Source: Myschool Past Questions Archive (Record #14531)