Question

In an experiment,the image of an object formed by concave mirror is obtained on a screen .to determine the focal lenght of the mirror, the experiment needs to measure the distance between the.

1. mirror and screen
2. mirror and object
3 both A and B
4 none of these .

Answer 1

I think ans is (3) .
We measure both distance and then find focal length by mirror formula.
I hope it will help u..