Question

A convex lens of focal length 20 cm is in contact with a concave lens of focal length 25cm . The power of combination of these lens is ?

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Answer 1

Answer:

Focal length of a convex lens,

F1=20

Focal length of a concave lens,

F2=25

power of a convex lens,

P1=100/F1

=100/20

=+5D

now,

power of a concave lens,P2=100/25

=-4D

therefore,

1)power of combination,P3=P1+P2

=5+(-4)

=1

2)focal length of combination=100/P3

=100/1

=100cm

therefore the ans of power of combination and focal length are 1 & 100 cm..

$this \: is \: your \: answer \:$

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