A typical 120-volt household circuit delivers 350 watts of power to an appliance, and another 10 watts of power are consumed by the circuit

As there is no ground fault, the same amount of current flows through the hot wire and the neutral wire.

a) Total power delivered to the appliance P = 350 W

Output voltage = 120 V

So the current drawn by the appliance, I = P/V = 350/120 = 2.92 Ampere -- Ans

Ground fault means some current is getting drained to ground. If that is the case, the current in Hot and neutral wires will not be equal.

In our case, both hot and neutral wire to the appliance carries

the same amount of current = 2.92 A -- Ans

Current through grounding conductor = 0 A -- Ans

The circuit consumes a power of 10W at 120 volt

Current consumed by the circuit I = P/V = 10/120 = 0.083 Ampere

Resistance of the circuit, R = V/I = 120/0.083 = 1445.8 Ohm -- Ans

Each bulb has a power rating of 500milli Watts on 120 V.

So the current required for one bulb is I = P/V = 0.5 Watts/120 Volt = 0.0042 A = 4.2mA

The total current drawn by 100 bulbs is then, I = 100 * 0.0042 = 0.42 Ampere

As there is no ground fault, the same amount of current flows through hot and neutral wire.

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Though the magnitude of current would be the same, they are opposite in direction. If you write a current I is flowing through the hot wire, you may say -I is flowing through the neutral wire. This is the principle behind the operation of Ground Fault Interrupters in your home.

As I and -I cancels, if you test for a magnetic field near a pair of hot and neutral wire, no net magnetic field will be there. If , for example, someone touches the hot wire, a ground leakage happens and the current through hot and neutral wires differs (hot wire has more current) and a net magnetic field is there. The sensing circuits detects this and switches off the Ground Fault Interrupter there by protecting the person.