Power in Electric Circuit

Electricity is the backbone of modern civilisation.

From industries to our homes, schools, offices, play stations and even our streats are illuminated by the electricity.

Everyday we use many appliances that run on electricity.

And this electricity do not come for free. We pay bills for the electricity consumption.

Let's understand the consumption of electrical energy

A battery stores the electrical energy which is consumed by the devices which get connected to it.

When we connect bulb to a battery , it starts glowing.

The bulb consumes the energy stored in the battery and converts it into heat and light.

The battery creates a potential difference across the bulbs and a current flows through it.

This current is made up of electric charges

Electrical charge while moving across resistor losses its energy

The rate at which the charge losses its energy, is the electrical power consumption

Suppose the potential across the bulbs at points 1 and 2 be and respectively.

Thus, the potential difference across the bulb will be given by

The potential energy of a charge flowing in the current at the point 1 and 2 will be given by

So, the change in potential energy of the charge across the resistor will be

This change in potential energy across resistor will convert into heat energy.

The rate of change of this potential energy gives the power consumed by the resistor of the bulb.

Since, current is the amount of charge flow per unit time.

Using ohm’s equation, the power equation can be rearrange as


Due to potential difference across the resistor, current is flowing thorough it.

The potential energy of the charges constituting the current dissipates as heat.

Power consumption in resistor having resistance and current flowing through it is .

If resistance is . The power consumption across resistor can be written in other form.

The End