College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 79

Suppose you want to use a converging lens to project the image of two trees onto a screen. One tree is a distance x from the lens; the other is at 2 x , as in Figure CQ23.7. You adjust the screen so that the near tree is in focus. If you now want the far tree to be in focus, do you move the screen toward or away from the lens