Question

Three capacitors of capacitances 3μF, 9μF, 18μF are connected once in series and then in parallel. The ratio of effective capacitance in the two cases ($\frac{Cs}{Cp}$) will be

a) 1:15

b) 15:1

c) 1:1

d) 1:3

Answer 1

1:15...................

Answer 2

1/ Cs = 1/3 + 1/9 + 1/ 18

= 1/2

Cs = 2

Cp = 9 + 18 + 3 = 30

Cs / Cp = 1 / 15

Option a