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Light Reflection and Refraction
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18/08/2021 12:51 pm
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An object placed 4 cm in front of a converging lens produces a real image 12 cm from the lens.
(a) What is the magnification of the image?
(b) What is the focal length of the lens?
(c) Draw a ray diagram to show the formation of image. Mark clearly F and 2F in the diagram.
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18/08/2021 12:57 pm
u = -4 cm
v = 12 cm (Real image)
(a) m = \(\frac{v}{u}\) = \(\frac{12}{-4}\) = -3
(b) \(\frac{1}{v}\) - \(\frac{1}{u}\) = \(\frac{1}{f}\)
\(\frac{1}{12}\) - \(\frac{1}{-4}\) = \(\frac{1}{f}\)
\(\frac{1 + 3}{12}\) = \(\frac{1}{f}\)
f = 3 cm
(c)