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Light Reflection and Refraction
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20/08/2021 1:16 pm
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Calculate the image distance for an object of height 12 mm at a distance of 0.20 m from a concave lens of focal length 0.30 m, and state the nature and size of the image.
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20/08/2021 1:21 pm
v = ?
\(h_1\) = 12 mm = 0.012 m
u = -0.20 m
f = -0.30 m
\(\frac{1}{v}\) - \(\frac{1}{u}\) = \(\frac{1}{f}\)
\(\frac{1}{v}\) - \(\frac{1}{-0.20}\) = \(\frac{1}{-0.30}\)
\(\frac{1}{v}\) = \(\frac{-1}{0.30}\) - \(\frac{1}{0.20}\)
v = -0.12 m
Image is virtual and erect.
m = \(\frac{h_2}{h_1}\) = \(\frac{v}{u}\)
\(\frac{h_2}{0.012}\) = \(\frac{-0.12}{-0.20}\)
\(h_2\) = 0.0072 m = 7.2 mm
Image is 7.2 mm high.