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प्रश्न
Express power of a concave lens of focal length 50 cm with its sign.
उत्तर
Power = `1/"focal length (in metres)"`
Now, a concave lens has a virtual focal length ; \ f = -50 cm
Power = `100/-50` = -2D
Powerof a concave lens is negative and the power is -2D.
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संबंधित प्रश्न
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