Question

Two convex lens of focal length 20 cm each are kept in contact with each other.find the power of combination

Answer 1

Answer:

Explanation:

F1=20cm

F2=20cm

P=1/F

1/F=1/F1+1/F2

    =1/20+1/20

    =1/10

P=1/10

=0.1*100

=10 D

Answer 2

Answer:

P=10D

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