An object, located 80.0 cm from a concave lens, forms an image 39.6 cm from the lens on the same side as the object. what is the focal length of the lens?

-78.4 cm

Explanation:

We can solve the problem by using the lens equation:

where

p is the distance of the object from the lens

q is the distance of the image from the lens

f is the focal length

Here we have

p = 80.0 cm

q = -39.6 cm (negative, because the image is on the same side as the object , so it is a virtual image)

Substituting, we find f:

photocells convert light energy to electricity

causes

fossil fuels burn

cities become more industrialized

human population grows worldwide