Find the position of the final image of the 1.0-cm-tall object

by Quizaza team | Last Updated: January 3, 2021

The figure shows a combination of two lenses. (Figure 1)

find the position of the final image of the 1.0-cm-tall object.

figure 1

 

Answer: THIS ANSWER WASN’T REVIEWED BY OUR EXPERTS!

1/f = 1/o = 1/di

find di of 1st lens

1/5 = 1/4 + 1/di

di = -20 cm (to left of 1st lens)

this plus distance between lenses is now the do for 2nd lens

20 + 12 = 32

then

1/-8 = 1/32 + 1/di

di = -6.4 cm

so final image is 6.4 cm LEFT of the 2nd lens [[1st answer]]

 

Find magnification of both lenses

M = – do/di

M1 = – (-20 / 4) = +5

M2 = – (-6.4 / 32) = +0.2

overall M is this product

M = M1 * M2 = 5 * .0.2 = 1

so the final image is the same size as the 1st object

summary

we have an upright image, 1.0 cm tall at 6.4 cm left of the 2nd lens.