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Two lenses with powers +12D and -2D are ...

Two lenses with powers +12D and -2D are kept in close contact with each other. Find the power and the focal length of the combination.

A

12 cm

B

10 cm

C

8 cm

D

15 cm

Text Solution

Verified by Experts

The correct Answer is:
B
For the two lenses in close contact, the power of combination `P=P_(1)+P_(2)=12-2=10D`
As `P=(1)/(f) therefore f=(1)/(P) =(1)/(10)m=10m`
`therefore f=10 cm`
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