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Light Reflection and Refraction
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11/08/2021 12:36 pm
Topic starter
If an object of 10 cm height is placed at a distance of 36 cm from a concave mirror of focal length 12 cm, find the position, nature and height of the image.
1 Answer
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11/08/2021 12:42 pm
\(h_1\) = 10 cm, u = 36 cm, f = 12 cm
We know that
\(\frac{1}{v}\) + \(\frac{1}{u}\) = \(\frac{1}{f}\)
\(\frac{1}{v}\) + \(\frac{1}{-36}\) = \(\frac{1}{-12}\)
\(\frac{1}{v}\) = \(\frac{1}{36}\) - \(\frac{1}{12}\)
= \(\frac{1 - 3}{36}\) = \(-\frac{2}{36}\) = \(-\frac{1}{18}\)
∴ The position of the image is 18 cm in front of the mirror.
Magnification, m = \(\frac{h_2}{h_1}\) = \(-\frac{v}{u}\)
=> \(\frac{h_2}{10}\) = \(-\frac{-18}{-36}\)
=> \(h_2\) = -5cm
The image formed is real and inverted.