If focal length of a biconvex lens are 20cm and 40cmr respectivily& refractive index is 1.5, then find the combination focal length of givenl lens?

Asked by narendra172193 | 9th Apr, 2021, 03:27: PM

Expert Answer:

focal length f of combination of lenses of focallengths f1 and f2 is given by
 
( 1 / f ) = ( 1 / f1 ) + ( 1 / f2 )
 
(1/f ) = ( 1/ 20 ) + ( 1/40)
 
We get  focal length f = ( 40/3 ) cm = 13.33 cm

Answered by Thiyagarajan K | 9th Apr, 2021, 04:58: PM

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