Ellen places an object 48.4 cm from a concave lens.If a virtual image appears 24.6 cm from the lens on the same side as the object,what is the focal length of the lens?
A)-16.3 cm
B)-50.0 cm
C)732 cm
D)-23.8 cm
E)-36.5 cm

Question

Quizplus · Accepted Answer

We can use the lens formula:

1/f = 1/do + 1/di

where f is the focal length, do is the object distance, and di is the image distance.

Since the image is virtual and on the same side as the object, di is negative.

Plugging in the given values, we get:

1/f = 1/48.4 - 1/24.6

Solving for f, we get:

f = -50.0 cm

Therefore, the answer is B.

Ellen Places an Object 48