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An astronomical telescope uses two lense...

An astronomical telescope uses two lenses of powers 10 dioptre and I dioptre. If the final image of a distant object is formed at infinity, calculate the length of the telescope.

Text Solution

Verified by Experts

Given `p_(e)=10` dipotre and `P_(0)=1` dioptre
We know, that,
`P_(e)=(1)/(f_(e))`
`10=(1)/(f_(e))`
`f_(e)=0*1 m=10 cm`
For objective lens, `P_(0)=(1)/(f_(0))`
`f_(0)=(1)/(1)=1m=100 cm`
So, `L=f_(0)+f_(e)=100+10`
=110 cm
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