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An astronomical telescope of magnifying ...

An astronomical telescope of magnifying power`8`is made using two lenses spaced `45cm`apart.The focal length of the lenses used are

A

`F=40cm f=5cm`

B

`F=8cm f=5cm`

C

`F=5cm f=40cm`

D

`F=20cm f=5cm`

Text Solution

Verified by Experts

The correct Answer is:
1
`M=(F)/(f)`
and`L=F+f=45cm`
`because M=8`
`F=8f`
`8f+f=45`
`:.f=5cm`
`:.F=40cm`
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