Want to ask us a question? Click here
Browse Questions
 Ad
0 votes

# A system of lens consists of two convex lenses of focal length $f_1= 30\;cm$ and $f_2 =20\;cm$. Separated by a distance 'd'. When a parallel beam of light is incident on the first lens after two refraction the resultant rays come out parallel then the distance 'd' is

$(a)\;40\;cm \\ (b)\;50\;cm \\ (c)\;30\;cm \\ (d)\;60\;cm$

Can you answer this question?

## 1 Answer

0 votes
For lens 1, the parallel beam will coverage at focus P at $f_1=30\;cm$ from lens 1, and these rays if they are at focus of 2nd lens , they  will be rendered parallel.
$\therefore 'd'= f_1+f_2$
$\qquad= 30+20 =50 cm$
Hence b is the question.

answered Jan 22, 2014 by
edited Jul 15, 2014

0 votes
1 answer

0 votes
1 answer

0 votes
1 answer

0 votes
1 answer

0 votes
1 answer

0 votes
1 answer

0 votes
1 answer