When the balance point is obtained in the potentiometer, a current is drawn from

In a series circuit, $R=300 \Omega, L=0.9 H,C=2.0 \mu F$ and $\omega=1000 rad/s$. The impedance of the circuit is 

$B_1, B_2$ and $B_3$ are three identical bulbs connected as shown in Figure 12.8. When all the three bulbs glow, a current of 3A is recorded by the ammeter A.

How much power is dissipated in the circuit when all the three bulbs glow together?

Heat energy is being produced in a resistance in a circuit at the rate of $100\ W$. The current of $2\ A$ is flowing in the circuit. what must be the value of the resistance (in $\Omega$)?