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Solve the following examples/ numerical ...

Solve the following examples/ numerical problems:
Two convex lenses of focal length 20 cm each are kept in contact with each other . Find the power of their combination .

Text Solution

Verified by Experts

The correct Answer is:
Power of combination is - 6.7 D.
Given: `f_(1)=f_(2)=-30 cm =-0.3 cm`
To find: Power of combination (P)
Formula: `P=(1)/(f)=(1)/(f_(1))+(1)/(f_(2))`
Calculation: From formula,
`P=(1)/(-0.3)+(1)/(0.3)=(-10)/(3)+(-10)/(3)`
`=(-20)/(3)=-6.7 D`
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