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प्रश्न
Two thin lenses having optical powers of -10D and+ 6D are placed in contact with each other. The focal length of the combination is:
विकल्प
+ 0·25 cm
- 0·25 cm
+ 0·25 m
- 0·25 m
उत्तर
Two thin lenses having optical powers of -10D and+ 6D are placed in contact with each other. The focal length of the combination is: - 0·25 m
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