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Light Reflection and Refraction
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17/08/2021 4:16 pm
Topic starter
A converging lens of focal length 5 cm is placed at a distance of 20 cm from a screen. How far from the lens should an object be placed so as to form its real image on the screen?
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17/08/2021 4:21 pm
f = 5 cm
u = -20
v = +v (since image is real)
\(\frac{1}{v}\) - \(\frac{1}{u}\) = \(\frac{1}{f}\)
\(\frac{1}{v}\) - \(\frac{1}{-20}\) = \(\frac{1}{5}\)
\(\frac{1}{v}\) = \(\frac{1}{5}\) - \(\frac{1}{20}\)
= \(\frac{4 - 1}{20}\)
= \(\frac{3}{20}\)
v = 6.66