Question

An illuminated object lies at a distance 1.0m from a screen. A convex lens is used to form a image of object on a screen placed at a distance of 75cm from the lens. Find the focal length and magnification

Answer 1

The focal length of the lens is 3m and the magnification of the lens is 0.75cm

Let the focal length of the convex lens is F

The distance between the object and the lens is U=1m=100cm

And the distance between screen is V=75cm

So the focal length can be derived for the convex lens is

1/F=1/V + 1/U

=>1/F=1/75 + 1/(-100)

=>1/F=1/300

=>F=300cm

So, F=3m

Focal length is 3m

Magnification of convex lens can be derived as M

We know magnification M= -(V/(-U))

=>M= 75/100

=>M= 0.75cm

Mark me as Brainliest