Question

The equivalent capacitance of the combination between A and B in the given figure is 15 μ F. Calculate the capacitance of capacitor C.

Answer 1

Since they are connected in Series,

1/Capacitance between A and B = 1/20 + 1/Capacitance at C

1/15 = 1/20 + 1/x

1/x = 1/15 - 1/20

1/x = 4-3/60

1/x = 1/60

x = 60

Therefore capacitance at C = 60 microFarell

Answer 2

Given: Equivalent capacitance of two capacitors connected in series =  15 μF

           One capacitance =  20 μF

To find: Another capacitance of capacitor

Solution:

The capacitance of two capacitors conncetd in series will always be less than the individual capacitance.

The voltage in series will be same in case of series in capacitance. Therefoe, the equivalent capacitance will be equal to 1/C' = 1/C₁ + 1/C₂

Where C' is the equivalent capacitance, C₁ is the capacitance of first capacitor, whereas C₂ is the capacitance of second capacitor.

Here the capacitors are in series, putting the values in the equation we get,

1/15 = 1/20 + 1/C₂

On solving the equation we get,

C₂ = 60 μF

Therefore, the capacitance of the second capacitor is 60 μF.