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A convex lens of focal length 25 cm is placed coaxially in contact with a concave lens of focal length 20 cm. Determine the power of the combination. Will the system be converging or diverging in nature ? |
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Answer» Solution :As `f_(1) = +25 cm` and `f_(2) = -20 cm` `RARR P_(1) = 100/(f_(1) cm) = +100/25 = +4D` and `P_(2) = 100/(f_(2)cm) = -100/20 = - 5D` `therefore` Power of the combination `P = P_(1) + P_(2) =+4D - 5D =-1D` The -ve sign of power SHOWS that the combination is behaving like a diverging lens. |
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