Electrical Energy and Power

Electrical Energy

From the definition of potential difference, the electric work is given by the formula:

W = QV

(W = Work done; Q = Charge; V = Voltage)

Since the work done must be equal to the energy to do the work, therefore we can also say that, the electrical energy ( E )is also given by the formula

Electrical Power

1. The electrical power, P is defined as the rates of energy that supply to the circuit ( or the rates of work been done ) by sources of electric.
2. The unit of electric power is the watt (W).
3. One watt of power equals the work done in one second by one volt of potential difference in moving one coulomb of charge.

Formulae of Electrical Power

Resistance and Power

In a series circuit, the higher the resistance of a resistor, the higher the power of the resistor.

In a parallel circuit, the higher the resistance of a resistor, the lower the power of the resistor.

Sum of Power

The effective power in a series circuit is equal to the sum of the power of each resistor in the circuit.

P = PR1 + PR2

Sum of power in a Parallel Circuit

The effective power in a parallel circuit is also equal to the sum of the power of each resistor in the circuit.

P = PR1 + PR2

Calculating The Cost Of Electricity Consumption

The cost of electricity consumption is based on the number of kilowatt-hours (kWh) of electrical energy used. The kilowatt-hours are sometimes known as the domestic units of electricity.

Formula