Question

Write the expression for electric power, when

1. Voltage and current given
2. Current and resistance given
3. Voltage and resistance given

Answer 1

Concept Used: Electric power

Step 1: Definition of electric Power:

Electric power $\left(\mathrm{P}\right)$ is defined as the rate at which the electric energy is transferred. Its SI unit is watt (W).

Step 2: Body of the solution:

a. Electric power expression, voltage, and current given,

Power is the product of voltage and current. Therefore $\mathrm{Power}\mathrm{P}=\mathrm{current}\left(\mathrm{I}\right)\times \mathrm{Voltage}\left(\mathrm{V}\right)$

b. Expression of electric Power in terms of current and resistance,

By Ohm's law, $\mathrm{V}=\mathrm{IR}$,

Therefore, Electric power in terms of voltage and resistance, $\mathrm{P}={\left(\mathrm{Current}\mathrm{I}\right)}^2\times \mathrm{Resistance}\mathrm{R}$

c. Expression for electric power, in terms of voltage and resistance,

Using Ohm's law, $\mathrm{I}=\frac{\mathrm{V}}{\mathrm{R}}$

Electric Power will be, $\mathrm{P}=\frac{{\left(\mathrm{Voltage}\mathrm{V}\right)}^2}{\mathrm{Resistance}\mathrm{R}}$