Question

An electric oven of $2kW$ power rating in a domestic electric circuit that has a current rating of $5A$. If the supply voltage is $220V$, what result do you expect? Explain.

Answer 1

The maximum current that could be passed through the oven is given as the current rating. Any current above this will break the fuse of the oven. We will find the current through the circuit by dividing maximum power with the voltage supply. This is obtained from the expression of power in which power is given as the product of current and voltage.

Complete step by step answer:
Firstly we will run the current through the circuit if the given voltage supply is connected to the oven and then we will compare this current with the current rating of the oven. If the current through the circuit is more than the current rating of the oven, the fuse in the circuit melts.
Now, to find the current through the circuit, we know that power is given as product of voltage and current
$P=VI$
To find the current,
$I=\dfrac{P}{V}=\dfrac{2kW}{220V}=\dfrac{2000}{220}>9A$
That is, when this voltage supply is connected to the circuit, more than $9A$ will be flowing through it. It is greater than the current rating. So the fuse melts and consequently, the circuit is broken and the electric oven is saved from getting damaged.

Note:
If we look at every electrical appliances in our home, most of them will be having a current rating. This is to protect them from damaging if a harmful source of voltage is connected. As we discussed, the fuse will melt and the circuit will be broken. Electrical appliances must be connected to a source which supplies current below its current rating.