Q 9.28  A small telescope has an objective lens of focal length 140cm and an eyepiece of focal length 5.0cm. What  is the magnifying power of the telescope for viewing distant objects when (a) the telescope is in normal adjustment (i.e., when the final image is at infinity)?

P Pankaj Sanodiya

Given,

the focal length of the objective lens $f_{objective}=140cm$

the focal length of the eyepiece lens $f_{eyepiece}=5cm$

normally, least distance of vision = 25cm

Now,

As we know magnifying power:

$m = \frac{f_{objective}}{f_{eyepiece}}=\frac{140}{5}=28$

Hence magnifying power is 28.

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