An astronomical telescope- consists of two thin lenses 36 cm a part and has a magnifying power 8- Calculate the focal length of the lenses-32 cm18 cm36 cm25 cm

Question

Toppr Admin · Accepted Answer

Here- fo-fe-36cmM-x2212-8 -magnifying power is negative-Now- M-fofe-x2234-x2212-8-x2212-8-x2212-fofe-x21D2-fo-8fe

An astronomical telescope, consists of two thin lenses set $36 c m$ a part and has a magnifying power $8$ . Calculate the focal length of the lenses.
$32 c m$
$18 c m$
$36 c m$
$25 c m$

Here, $f_{o} + f_{e} = 36 c m$
$M = - 8$ (magnifying power is negative)
Now, $M = \frac{f_{o}}{f_{e}}$
$∴ - 8 = - 8 = - \frac{f_{o}}{f_{e}}$
$\Rightarrow f_{o} = 8 f_{e}$

An astronomical telescope, consists of two thin lenses set 36cm a part and has a magnifying power 8. Calculate the focal length of the lenses.32cm18cm36cm25cm

Here, fo+fe=36cmM=−8 (magnifying power is negative)Now, M=fofe∴−8=−8=−fofe⇒fo=8fe

An astronomical telescope, consists of two thin lenses set $36 c m$ a part and has a magnifying power $8$ . Calculate the focal length of the lenses.
$32 c m$
$18 c m$
$36 c m$
$25 c m$

Here, $f_{o} + f_{e} = 36 c m$
$M = - 8$ (magnifying power is negative)
Now, $M = \frac{f_{o}}{f_{e}}$
$∴ - 8 = - 8 = - \frac{f_{o}}{f_{e}}$
$\Rightarrow f_{o} = 8 f_{e}$