Question

What do you mean by power rating of an electrical appliance? How do you use it to calculate (a) the resistance of the appliance, and (b) the safe limit of current in it, while in use?

Answer 1

The rating of an electrical appliance indicates the voltage at which the appliance is designed to work and the power consumption at that voltage.

(a) $\text{Resistance}=\frac{(\text{Voltage rating of the appliance}{)}^2}{\text{Power rating of the appliance}}$

(b) $\text{Safe current}=\frac{\text{Power rating of the appliance}}{\text{Voltage rating of the appliance}}$