Request a call back

Join NOW to get access to exclusive study material for best results

CBSE Class 10 Answered

Prove that R=2f
Asked by cool_mohit981994 | 14 Apr, 2009, 08:01: PM
answered-by-expert Expert Answer

You can't actually prove it. And it never is (practically). It's just close enough for physics.

But , an approximate derivation could be done.

A ray of light passing parallel to the principal axis and close to the principal axis after incident at a point Q on the mirror is reflected according to the law of reflection ( i = r ) and passes through the focus F.

If O is the center of curvature of the mirror, consider the triangle OQF.

Angle OQf = r the angle of reflection.

Angle QOf = i the angle of incidence (the line OQ passes through two parallel lines). And therefore the Angle Angle QOf = i

As i = r the triangle is a isosceles tri angle and hence QF = OF

If P is the pole of the mirror, considering large radius of curvature we can take PF =QF and hence OF = PF or half the radius of curvature.
Answered by | 23 Apr, 2009, 02:35: PM
CBSE 10 - Physics
Asked by suryamr2019 | 08 Mar, 2024, 04:32: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Physics
Asked by nandanagnair | 17 Dec, 2023, 03:44: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Physics
Asked by 0 0 | 19 Oct, 2023, 03:51: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Physics
Asked by bubbynaik77 | 29 Sep, 2023, 09:34: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Physics
Asked by gurcharansingh37306 | 10 Sep, 2023, 12:53: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Physics
Asked by Shiwani.Sawant | 28 Jul, 2023, 09:42: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
Get Latest Study Material for Academic year 24-25 Click here
×