A converging lens with a focal length of 9 cm is used to make a slide projector.?

Question

\If the image is to be projected onto a screen 4.6 m away, how far from the lens should the slide be placed in cm?Can anyone help me tackle this problem?

Answer 1

1/p+1/q=1/f

1/p+1/460=1/9

solve for p

Answer 2

1/do + 1/di = 1/f

f = focal length, do is object distance and di is image distance from the lens.

In your case, the object distance is the distance from the slide to the lens, and the image distance is the distance to the screen.