Question

In order to determine the focal length of a concave mirror by obtaining the image of distant object on screen, the position of screen should be
(a) parallel to the plane of concave mirror
(b) perpendicular to the plane of a concave mirror
(c) inclined at an angle 60° to plane of the mirror
(d) in any direction with respect to the plane of concave mirror and please explain why?

Answer 1

Answer:

A is the answer acc to me...

as to the img formed will be at focus bcz object is at infinity..and the image is diminished so the screen should bi parallel to plane of mirror