Question

Three capacitors of capacitances $3\,\mu F$,$9\,\mu F$ and $18\,\mu F$ are connected once in series and another time in parallels. The ratio of equivalent capacitances in the two cases $(C_s/C_p)$ will be

• A. 1:15
• B. 15:01
• C. 1:01
• D. 1:03

Answer 1

Answer: (A)

1:15

Answer 2

$\frac{1}{C_s} = \frac{1}{3} + \frac{1}{9} + \frac{1}{18} = \frac{1}{2}$ . Hence $C_s = 2 \, \mu F$ $C_p = 3 + 9 + 18 = 30 \, \mu F$ Therefore $C_s /C_p$ = 2/30 = 1 /15.