# A student has to project a three times magnified image of a candle flame on a wall. Name the type of the lens (converging/ diverging) required for the purpose. It the candle flame is at a distance of 6 m from the wall, find the focal length of the lens.... .plzz dont send any links

As the student want three times magnified image, so student have to image us the convex lens (converging lens)

$letm=\frac{-v}{u}\phantom{\rule{0ex}{0ex}}3=\frac{-v}{u}\phantom{\rule{0ex}{0ex}}v=-3u\phantom{\rule{0ex}{0ex}}fromthequestion\phantom{\rule{0ex}{0ex}}u+v=6\phantom{\rule{0ex}{0ex}}u-3u=6\phantom{\rule{0ex}{0ex}}u=-3\phantom{\rule{0ex}{0ex}}fromthemirrorformula\phantom{\rule{0ex}{0ex}}\frac{1}{v}-\frac{1}{u}=\frac{1}{f}\phantom{\rule{0ex}{0ex}}\frac{1}{9}+\frac{1}{3}=\frac{1}{f}\phantom{\rule{0ex}{0ex}}\frac{4}{9}=\frac{1}{f}\phantom{\rule{0ex}{0ex}}f=\frac{9}{4}\phantom{\rule{0ex}{0ex}}\phantom{\rule{0ex}{0ex}}$

focal length f=9/4

Regards

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