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प्रश्न
The lens of power + 1·0 D is ______.
विकल्प
Convex of focal length 1·0 cm
Convex of focal length 1·0 m
Concave of focal length 1·0 cm
Concave of focal length 1·0 m.
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उत्तर
The lens of power + 1·0 D is convex of focal length 1·0 m.
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संबंधित प्रश्न
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