JAMB - Physics (2011 - No. 43)
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?
10 cm
25 cm
16 cm
14 cm
설명
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
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