Electrostatics Question 531
Question: Three capacitors of capacitances $ 3\mu F,\ 9\mu F $ and $ 18\mu F $ are connected once in series and another time in parallel. The ratio of equivalent capacitance in the two cases $ ( \frac{C _{s}}{C _{p}} ) $ will be [CPMT 1990]
Options:
A) 1 : 15
B) 15 : 1
C) 1 : 1
D) 1 : 3
Show Answer
Answer:
Correct Answer: A
Solution:
$ \frac{1}{C _{s}}=\frac{1}{3}+\frac{1}{9}+\frac{1}{18}=\frac{1}{2} $
therefore $ C _{s}=2\mu F $
$ C _{p}=3+9+18=30\mu F $
therefore $ \frac{C _{s}}{C _{p}}=\frac{2}{30}=\frac{1}{15} $
