Use app×
Join Bloom Tuition
One on One Online Tuition
JEE MAIN 2025 Foundation Course
NEET 2025 Foundation Course
CLASS 12 FOUNDATION COURSE
CLASS 10 FOUNDATION COURSE
CLASS 9 FOUNDATION COURSE
CLASS 8 FOUNDATION COURSE
0 votes
76 views
in Physics by (93.5k points)
closed by
Two thin sysmmetrical lenses of different nature and of different material have equal raii of curvature `R=15cm`. The lenses are put close together and immersed in water `(mu_(w)=4//3)` . The focal length of the system ini water is 30cm. The difference between refractive indices of tthe two lenses is
A. `(1)/(2)`
B. `(1)/(4)`
C. `(1)/(3)`
D. `(3)/(4)`

1 Answer

0 votes
by (93.9k points)
selected by
 
Best answer
Correct Answer - A
Let `f_(1)` and `f_(2)` be the focal length in water.
Then
`(1)/(f_(1))=((mu_(1))/(mu_(w))-1)((1)/(R)+(1)/(R))=((mu_(1))/(mu_(w))-1)((2)/(R))` ....`(1)`
`(1)/(f_(1))=((mu_(2))/(mu_(w))-1)(-(1)/(R)+(1)/(R))=((mu_(2))/(mu_(w))-1)(-(2)/(R))` ....`(2)`
Adding `(1)` and `(2)` we get
`(1)/(f_(1))+(1)/(f_(2))=(2(mu_(1)-mu_(2)))/(mu_(w)R)`
or `(1)/(30)=(2(mu_(1)-mu_(2)))/(mu_(w)R)`
`:. (mu_(1)-mu_(2))=(mu_(w)R)/(60)`
Substituting the values
`(mu_(1)-mu_(2))=(4xx15)/(3xx60)=(1)/(3)`

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

Categories

...