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Physics LibreTexts

2.8C: Power of a Mirror

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In Figure II.13 shows a reflecting surface of radius of curvature r submerged in a medium of index n. I show a real object at O, a virtual image at I and the centre of curvature at C. We see that h=αp=βq=γr. By Euclid, θ=α+γ and 2θ=α+β. Remember again that all angles are supposed to be small (even β!), in spite of the drawing. From these we obtain

1q=1p+2r.

On multiplying this by n, we find that the power is 2n/r. Again the reader should try this for other situations, such a concave mirror, or a real image, and so on. The same result will always be obtained.

FIGURE 11.13 .png


This page titled 2.8C: Power of a Mirror is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Jeremy Tatum via source content that was edited to the style and standards of the LibreTexts platform.

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