An object 50-cm high is placed 1.0 m in front of a converging lens whose focal length is 1.5 m. Determine the image height (in cm).
A) 77
B) 150
C) 52
D) 17
E) 83

Question

Quizplus · Accepted Answer

Using the thin lens equation: 
1/d0 + 1/di = 1/f 
where d0 is the object distance, di is the image distance, and f is the focal length.

Substituting the given values, 
1/1 + 1/di = 1/1.5

Solving for di, 
di = 3 m

Using the magnification equation: 
m = -di/d0

Substituting the given values, 
m = -3/1

m = -3

The negative sign indicates that the image is inverted.

Using the equation for image height: 
hi = |m| * ho

Substituting the given values, 
hi = 3 * 50 cm

hi = 150 cm

Therefore, the image height is 150 cm or 1.5 m. The correct answer is (B).

An Object 50-Cm High Is Placed 1