When a ray of light travel parallel to the principal axis of a concave mirror strikes at the polished surface of mirror what is the reflected ray?

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Text Solution

`(R)/(2)``(Rcostheta)/(2)``(R)/(2costheta)``(R)/(2)(1+costheta)`

Answer : C

Solution : <img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/CPS_V02_C16_E01_067_S01.png" width="80%"> <br> Here `theta` is not small <br> In `DeltaACB,(d)/(sintheta)=(R)/(sin(pi-2theta))` <br> `(d)/(sintheta)=(R)/(sin2theta=2sinthetacostheta)` <br> `d=(R)/(2costheta)` <br> As `thetararr0,drarr(R)/(2)=f`