Question

Two identical capacitors of 12 pF each are connected in series across a battery of 50 V. How much electrostatic energy is stored in the combination? If these were connected in parallel across the same battery, how much energy will be stored in the combination now?

Also find the charge drawn from the battery in each case.

Answer 1

Series combination

In series combination, Equivalent capacitance, C_eq would be given as 

`C_"eq"= (C_1C_2)/(C_1+C_2)`

`= (12×12)/(12+12)`

`= 6 pF`

Electrostatic energy stored in the series combination would be 

=`12C_"eq"V^2 `

`= 12×6×10^-12×50^2`

`= 7.5×10^-9 "Joule"`.

Charge drawn from battery in series combination, 

`Q = C_"eq"V`

`= 6×10^-12×50`

`= 3×10^-10 C`