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| Mirror Formula |
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| A formula giving the relation between focal length of the mirror, object distance, image distance and radius of curvature. |
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| Depending on the position of the object, the image formed may be real or virtual. |
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| When the object is placed beyond 'C', the image is formed between 'C' and 'F'. Since the reflected rays actually meet at A', the image is said to be real. |
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| from the above two equations we have |
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| Since all distances are measured from P |
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| CB = PB - PC |
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| CBl = PC - PBl |
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| Therefore, |
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| Using the sign convention, |
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| PB = - u (object distance) |
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| PC = -R |
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| PB = -v (Image distance) |
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| On substitution, |
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| +uR - uv = uv - vR |
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| uR + vR = 2uv |
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| Dividing both sides by uvR, we have |
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| where f is the focal length of the mirror. |
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| Note: The above mirror formula is same for convex mirror for which image is always virtual. |
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