reflection from spherical mirror and find relation between F and R
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according to law of reflection,
angle of incidence = angle of reflection.
e.g.,![\angle i=\angle r \angle i=\angle r](https://tex.z-dn.net/?f=%5Cangle+i%3D%5Cangle+r)
in ∆BCF,
it is clear that, AB is parallel to CP
so,
[alternate angles ]
so,![\angle\alpha=\angle r \angle\alpha=\angle r](https://tex.z-dn.net/?f=%5Cangle%5Calpha%3D%5Cangle+r)
thus, BCF is an isosceles triangle.
so, CF = FB
now, of the aperture of the mirror is small, then B lies close to P, so that ,
FB ≈ FP
so,![FP=CF=\frac{1}{2}CP FP=CF=\frac{1}{2}CP](https://tex.z-dn.net/?f=FP%3DCF%3D%5Cfrac%7B1%7D%7B2%7DCP)
here,![FP=\textbf{focal length,f} FP=\textbf{focal length,f}](https://tex.z-dn.net/?f=FP%3D%5Ctextbf%7Bfocal+length%2Cf%7D)
and![CP=\textbf{radius of curvature,R} CP=\textbf{radius of curvature,R}](https://tex.z-dn.net/?f=CP%3D%5Ctextbf%7Bradius+of+curvature%2CR%7D)
e.g.,
angle of incidence = angle of reflection.
e.g.,
in ∆BCF,
it is clear that, AB is parallel to CP
so,
so,
thus, BCF is an isosceles triangle.
so, CF = FB
now, of the aperture of the mirror is small, then B lies close to P, so that ,
FB ≈ FP
so,
here,
and
e.g.,
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