The power of a combination of two lenses in contact is + 1:0 D. If the focal length of one of the lenses of the combination is + 20 cm, the focal length of the other lens would be: (a) - 120.0 cm (
b) + 80-0 cm (
c) - 25.0 cm (
d) - 20-0 cm
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2
Option b) +80-0cm is the answer
(Hope this helped)
Answered by
2
Power of lens with f = +20cm = +5D
.: the power of other lens = 1-5 = -4D
Focal length of lens with -4D = -25cm
(Note: power of combination of lens:- P = P1+P2)
.: answer is option (c)
.: the power of other lens = 1-5 = -4D
Focal length of lens with -4D = -25cm
(Note: power of combination of lens:- P = P1+P2)
.: answer is option (c)
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