In: Physics
A converging lens whose focal length f = 20 cm projects a 3.0 times magnified image of an object on a screen. What is the distance q from the screen to the lens and the distance p from the object to the lens?
Solution:
Given, the focal length of the lens
The magnification is 3.
Since the lens is convex, magnification .
The object distance and image distance are and .(v=q, u=p)
The magnification for the lens is given by,
i.e,
...............................(1)
From the lens formula,(v=q, u=p)
.....................(2)
Substituting for from (1), we have eq.(2) as
So,
The value of is