Question

a concave lens of focal length 25cm and a convex lens of focal length 20cm are in contact find the power of combination.also find the focal length of combination​

Answer 1

Answer:

$\frac{1}{f} = \frac{1}{f1} - \frac{1}{f2} \\ \: \: = \frac{1}{20} - \frac{1}{25} \\ \: \: = \frac{1}{100} \\ \: \: f = 100 = 1m \\ p = \frac{1}{f} \\ 1d$

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