Electrical Engineering ⇒ Topic : Joining Two Charged Capacitors

Joining Two Charged Capacitors

Consider two charged capacitors of capacitances C₁ and C₂ charged to potentials V₁, and V₂ respectively as shown in Figure (a) With switch S open,

                                      Q₁, = C₁, V₁, and Q₂ = C₂V₂

                                             figure (a)

When switch Sis closed, positive charge will flow from the capacitor of higher potential to the capacitor of lower potential. This flow of charge will continue till p.d. across each capacitor is the same. This is called common potential (V).

The following points may be noted :

• Although there is a redistribution of charge on connecting the capacitors (i. e., closing switch S), the total charge before and after the connection remains the same (Remember charge is a conserved quantity). This means that charge lost by one capacitor is *equal to the charge gained by the other capacitor.
• When switch S is closed, the capacitors are in parallel.
• Since the two capacitors acquire the same common potential F
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• Therefore, the charges acquired by the capacitors are in the ratio of their capacitances.
• In this process of charge sharing, the total stored energy of the capacitors decreases. It is because energy is dissipated as heat in the connecting wires when charge flows from one capacitor to the other.