A plant that is 4.1 cm tall is 10.3 cm from a converging lens. You observe that the image of this plant is virtual and 6.2 cm tall. What is the focal length of the lens?
A) 30 cm
B) 6.8 cm
C) 16 cm
D) -30 cm
E) -16 cm

Question

Quizplus · Accepted Answer

The image is virtual and upright, so the lens is diverging. The magnification is -6.2 cm / 4.1 cm = -1.51. The focal length is given by f = -d_i / m = -10.3 cm / -1.51 = 6.8 cm.

A Plant That Is 4