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Light Reflection and Refraction
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17/08/2021 3:37 pm
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An object 4 cm high is placed at a distance of 10 cm from a convex lens of focal length 20 cm. Find the position, nature and size of the image.
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17/08/2021 3:42 pm
u = -10 cm
\(h_1\) = 4 cm
f = 20 cm
\(\frac{1}{v}\) - \(\frac{1}{u}\) = \(\frac{1}{f}\)
\(\frac{1}{v}\) - \(\frac{1}{-10}\) = \(\frac{1}{20}\)
\(\frac{1}{v}\) = \(\frac{1}{20}\) - \(\frac{1}{10}\) = -\(\frac{1}{20}\)
v = -20 cm (Image is 20 cm in front of the convex lens)
m = \(\frac{v}{u}\) = \(\frac{20}{-10}\) = -2
m = \(\frac{h_2}{h_1}\) = -2
\(\frac{h_2}{4}\) = -2
\(h_2\) = -8 cm
Image is 8 cm in size and real and inverted.