Question

Focal length of lens having power-10D will be-
a) 10cm b) 10mc) -10cm d) -10m
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Answer 1

Answer:

we know

power = 1/ focal length

10 D =1/focal length

10×1=focal length

focal length=10 m

Answer 2

Answer:

focal length of lens having power -10D

p=100/f

p=-10D

-10=100/f

f=100/-10

f=-D

f=-(-10)

focal length=10