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Two convex lenses of focal lengths 25 cm...

Two convex lenses of focal lengths 25 cm and 15 cm are placed in contact with each other. Find the focal length of combination.

Text Solution

Verified by Experts

The correct Answer is:
Focal length of combination is 9.375 cm.
Given: `f_(1)=25 cm, f_(2)=15 cm`
To find: Focal length of combination (f)
Formula: `(1)/(f)=(1)/(f_(1))+(1)/(f_(2))`
Calculation: From formula,
`(1)/(f)=(1)/(25)+(1)/(15)=(3)/(75)+(5)/(75)=(8)/(75)`
`therefore" "f=(75)/(8)=9.375 cm`
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