logo

Ask Questions, Get Answers

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

A hollow double concave lens is made of very thin transparent material It can be filled with air or either of two liquids $L_1$ or $L_2$ having refracting indices $n_1$ and $n_2$ respectively $( n_2 > n_1 > 1)$ The lens will diverge a parallel beam of light if it is filled with

(a) $L_2$ and immersed in $L_1$ (b)air and immersed in $L_1$ (c) $L_1$ and immersed in $L_2$ (d)air and placed on air

Can you answer this question?
 
 

1 Answer

0 votes
The makers formula is
$\large\frac{1}{f} =\bigg( \large\frac{n_L}{n_m}-1 \bigg) \bigg( \frac{1}{R_1}-\frac{1}{R_2}\bigg)$
Where $ n_L$= Refractive index of lens and
$n_m$= Refractive index of medium .
In case of double concave lens $R_1$ is negative and $R_2$ is positive.
$\therefore \bigg( \large \frac{1}{R_1}-\large\frac{1}{R_2} \bigg) $ will be negative.
For the lens to be diverging in nature, focal length 'f' should be negative or $\bigg( \large\frac{n_L}{n_m}-1 \bigg)$ should be +ve or $n_L > n_m$ but since $n_2 > n_1 (given)$
$\therefore $ the lens should be filled with $L_2$ and immersed in $L_1$
Hence a is the correct answer.

 

answered Feb 19, 2014 by meena.p
edited Jul 24, 2014 by thagee.vedartham
 

Related questions

Ask Question
student study plans
x
JEE MAIN, CBSE, NEET Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App
...