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 $\Omega$)?

$220 \mathrm{~V}-60 \mathrm{~W}$ ও $220 \mathrm{~V}-80 \mathrm{~W}$ এর ২টি বাল্ব 1টি 220V উৎসের সাথে শ্রেণিতে যুক্ত আছে।

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

$B_1, B_2$ 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?

The resistance of the filament of an electric bulb changes with temperature. If an electric bulb rated $220 \ V$ and $100 \ W$ is connected to $(220\times 0.8) \ V$ source, then the power would be :