In general, power is defined as the rate of doing work or rate of spending energy. Similarly, the electric power is defined as the rate of consumption of electrical energy. It represents the rate at which the electrical energy is converted into some other form of energy.

**ELECTRIC POWER**

In general, power is
defined as the rate of doing work or rate of spending energy. Similarly, the
electric power is defined as the rate of consumption of electrical energy. It
represents the rate at which the electrical energy is converted into some other
form of energy.

Suppose a current â€˜Iâ€™
flows through a conductor of resistance â€˜Râ€™ for a time â€˜tâ€™, then the potential
difference across the two ends of the conductor is â€˜Vâ€™. The work done â€˜Wâ€™ to
move the charge across the ends of the conductor is given by the equation
(4.19) as follows:

W = VIt,

Power P = Work / Time =
VIt/t

**P = V I** (4.21)

Thus, the electric power
is the product of the electric current and the potential difference due to
which the current passes in a circuit.

The SI unit of electric
power is watt. When a current of 1 ampere passes across the ends of a
conductor, which is at a potential difference of 1 volt, then the electric
power is

P = 1 volt Ã— 1 ampere =
1 watt

Thus, one watt is the
power consumed when an electric device is operated at a potential difference of
one volt and it carries a current of one ampere. A larger unit of power, which
is more commonly used is kilowatt.

Electricity is consumed
both in houses and industries. Consumption of electricity is based on two
factors: (i) Amount of electric power and (ii) Duration of usage. Electrical
energy consumed is taken as the product of electric power and time of usage.
For example, if 100 watt of electric power is consumed for two hours, then the
power consumed is 100 Ã— 2 = 200 watt hour. Consumption of electrical energy is
measured and expressed in watt hour, though its SI unit is watt second. In
practice, a larger unit of electrical energy is needed. This larger unit is
kilowatt hour (kWh) . One kilowatt hour is otherwise known as one unit of
electrical energy. One kilowatt hour means that an electric power of 1000 watt
has been utilized for an hour. Hence,

1 kWh = 1000 watt hour =
1000 Ã— (60 Ã— 60) watt second = 3.6 Ã— 10^{6} J

Tags : Definition, Formula, Unit, Consumption , 10th Science : Chapter 4 : Electricity

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10th Science : Chapter 4 : Electricity : Electric Power | Definition, Formula, Unit, Consumption

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