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Optical instruments : telescope - class-IX
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A reflecting telescope has a large mirror for its objective with radius of curvature equal to 80 cm. The magnifying power of this telescope if eye piece used has a focal length of 1.6 cm is:
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A
25
💡 Explanation:
The focal length of objective mirror $f _0 = \dfrac{R}{2} = \dfrac{80}{2} = 40 ,cm$
and focal length of eye piece = 1.6 cm
$\therefore $ magnifying power, $m = \dfrac{f _0}{f _e} = \dfrac{40}{1.6 } = 25$