An object 20-cm high is placed 50.0 cm in front of a lens whose focal length is 5.00 cm. Where will the image be located (in cm)?
A) 5.13
B) 5.56
C) 5.72
D) 5.93
E) 4.55

Question

Quizplus · Accepted Answer

Using the thin lens equation: 
1/f = 1/di - 1/do 
where f is the focal length, di is the image distance, and do is the object distance. 
Plugging in the given values: 
1/5 = 1/di - 1/50 
Solving for di: 
di = 5.56 cm 
Therefore, the image will be located 5.56 cm in front of the lens. Choice B is the closest to this value.

An Object 20-Cm High Is Placed 50