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Answer» Answer: Mirror FORMULA is the RELATIONSHIP between image distance (v), focal length (f) and OBJECT distance (u) .Explanation: Mirror formula: 1/v+1/u=1/f Where image distance (v), focal length (f) and object distance (u). Proof of the mirror formula (considering CONCAVE mirror): In ΔABC and ΔA′B′C′ ΔABC ∼ ΔA′B′C [AA similarity] AB / A′B′=AC / A′C′ ------------------- (1) Similarly, In ΔFPEand ΔA′B′F′ EP / A′B′=PF / A′F AB / A′B′=PF / A′F [ AB=EP] ------------- (2) From (1) and (2) AC / A′C=PF / A′F =>A′C / AC=A′F / PF =>(CP−A′P) / (AP−CP)=(A′P–PF) /PF Now, PF =−f; CP =2PF=−2f ; AP=−u ; and A′P= −v Put these value in above RELATION: ⟹[(−2f)–(−v)] / (−u)−(−2f) = [(−v)–(−f)] / (−f) ⟹uv=fv+uf ⟹1 / f=1 / u + 1 / v Learn more about mirror formula: |
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