Question
Question: Two thin lens have a combined power of 10 D in contact. When separated by 20 cm their equivalent pow...
Two thin lens have a combined power of 10 D in contact. When separated by 20 cm their equivalent power is 6.25 D. Find their individual powers in dioptres –
A
3.5and 6.5
B
5 and 5
C
7.5 and 2.5
D
9 and 1
Answer
7.5 and 2.5
Explanation
Solution
P = P1 + P2 Ž 10 = 
+ 
P = P1 + P2 – d P1P2 Ž 6.25 = 
+ 
On solving (3) option is obtained