Question

Why is the focal length of a plane mirror infinity?

Answer 1

heya,...

Focal length of plane mirror will be infinity

because focal lenght means the distance between the radius of curvature to the mirror.but a plane mirror have no radius ,if you want to find its radius then you will be go to infinity then the radius is find where are you radius find then it must be it's focal length but you can't find its radius .because it will at infinity.


hope it help you.

.@rajukumar.☺

Answer 2

hii

We all learned that the focal length of plane mirrors is considered to be infinite, as the radius of curvature is infinite. However, imagine this scenario: You have a perfectly flat (no one get mad, this is theoretical)plane mirror, and the earth is perfectly flat as well(theoretical). If you looked into this mirror with a telescope (imagine it is powerful enough), would you be able to see as far away as you wanted to, just as if you were looking into reality? I know that spherical apertures are limited by Lord Rayleigh's criterion (after all, only so many photons can be recorded onto a surface), so are plane mirrors limited by this as well? If so, then we should call the focal length of a plane mirror something besides infinite, right?

and tht's ur answer. hope it helps u