Question

Three students A,B and C focussed a distant building on a screen with the help of a concave mirror. To determine focal length of the concave mirror they measured the distances as given below:Student A : From mirror to the screen
Student B : From building to the screen
Student C : From building to the mirror
Who measured the focal length correctly ;
(a) Only A
(b) Only B
(c) A and B
(d) B and C

Answer 1

HEY MATE HERE IS YOUR ANSWER!!!!
Option (A) is the correct answer because the focal length of a mirror is equal to the distance between the mirror and the screen....
HOPE IT HELPS YOU MATE!!!

Answer 2

Hope this helps you

It is attached