Capacitors in parallel:
Three capacitors are connected in parallel. If on closing the switch S a current I flows in the circuit, then from Kirchoff's first law:
I = I_{1} + I_{2} + I_{3}
therefore It = I_{1}t + I_{2}t + I_{3}t (where 't' is the time)
but Q = It
therefore Q_{TOTAL} = Q_{1} + Q_{2} + Q_{3}
therefore
but Q/V = C
Therefore C = C_{1} + C_{2} + C_{3}
Thus, we may replace capacitors in parallel by a single capacitor whose value is given by the above equation.