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Light Reflection and Refraction
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11/08/2021 7:23 pm
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A bright object 50 mm high stands on the axis of a concave mirror of focal length 100 mm and at a distance of 300 mm from the concave mirror. How big will the image be?
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11/08/2021 7:28 pm
\(h_1\) = 50 mm, f = 100 mm, u = 300 mm,
\(h_1\) = ?
We have
\(\frac{1}{v}\) + \(\frac{1}{u}\) = \(\frac{1}{f}\)
\(\frac{1}{v}\) + \(\frac{1}{-300}\) = \(\frac{1}{-100}\)
\(\frac{1}{v}\) = \(\frac{1}{300}\) - \(\frac{1}{100}\)
\(\frac{1}{v}\) = \(\frac{-200}{30000}\)
\(\frac{1}{v}\) = \(\frac{-2}{300}\)
v = -150 mm
m = -\(\frac{v}{u}\) = \(\frac{h_2}{h_1}\)
= \(\frac{-150}{-300}\) = \(\frac{h_2}{50}\)
The image will be 25 mm high.