Loss of Energy on Sharing of Charges between the Capacitors in Parallel: Consider two capacitors of capacitances C1, C2, charges q1, q2 and potentials V1,V2.
Total charge after sharing = Total charge before sharing
V is known as common potential.
Therefore, there is some loss of energy when two charged capacitors are connected together. The loss of energy appears as heat and the wire connecting the two capacitors may become hot.