Question

What is Electric Power? Give its unit. Explain how the electricity consumed by an appliance can be calculated.

Answer 1

ELECTRIC POWER

1. The amount of Electrical Energy flowing in a circuit per unit of time denotes the power of the appliance.
2. Thus we can define Electric power as Electrical Energy consumed per unit time by an electrical Appliance.

• Power = Electrical Energy ⁄Time or
• P = E/T

UNIT OF POWER

• SI UNIT - Electrical Energy -joule (J)
• Time - Second (s)

Thus, the SI unit of Power is Joule per second (J s^-1 ) or Watt.

So when an Electrical Appliance consumes Electrical Energy of one joule in one second its power is said to be one watt.

Calculation of the consumption of electricity by the appliance used;

1. Electricity meter is the device used to calculate the electricity consumption in kilowatt-hour (kWh).
2. One-kilowatt hour of electrical energy is consumed if an instrument with a power rating of one kilowatt is used for one hour.
3. One kilowatt-hour is also known as one unit.
4. The amount of units consumed in a house is read from the electric meter every month and the electricity bill is generated.

Energy consumed (KWh)=Power(KW)×Time(h)

Total cost= Total units×Cost of Each unit.