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प्रश्न
The power of a lens is +2.0D. Its focal length should be :
पर्याय
100 cm
50 cm
25 cm
40 cm
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उत्तर
50 cm
Focal length `=1/"power"=1/2.0=0.5m=50cm`
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संबंधित प्रश्न
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