Question

Two identical diverging lenses are separated by 16 cm. The focal length of each lens is -8.0 cm. An object is located 4.0 cm to the left of the lens that is on the left. Determine the final image distance relative to the lens on the right.
cm

please explain in detail. thanks

Answer 1

For the first lens, apply 1/f = 1/p + 1/q

1/-8 = 1/4 + 1/q

q = -2.67 cm

That means the first image is 2.67 cm in front of the first lens.

Since the lenses are 16 cm apart, that means that image is the object for the second lens and is 18.67 cm in front of it.

SO apply the lens equation for the second lens

1/-8 = 1/18.67 + 1/q

q = -5.60 cm

That means the final image is 5.60 cm to the left of the second lens