Question

A slide projector needs to create a 84-cm-high image of a 2.0-cm-tall slide. The screen is 330 cm from the slide.

How far should you place the lens from the slide?

What focal length does the lens need? Assume that it is a thin lens.

Answer 1

Answer:

Here we are using two relations

magnification is ratio of image height and object height as well as image distance and object distance. Which can be expressed mathematically as follows

another one is between focal length image distance and object distance

ie

lets start solving the first part

we know from the given data that

and

&

ie

&

ie lens should be kept 7.674cm away from the slide

partII

focal length of 7.495cm is required