If a.b.c source of 7V is connected across AB, how much charge is drawn from the source and what is the energy stored in the network ?

Explanation

If the voltage across AB be V = 7 V, then net charge drawn from the voltage source
`Q = CV = (6/7 muF) xx (7 V) = 6 muC`
and the energy stored in the network `u = 1/2 QV = 1/2 xx(6 muC) xx (7 V) = 21 muJ`