In physics, electric power measure of the rate of electrical energy transfer by an electric circuit per unit time. Denoted by P and measured using the SI unit of power is the watt or one joule per second. Electric power is commonly supplied by sources such as electric batteries and produced by electric generators.
Electric Power Definition
Electric power is the rate at which work is done or energy is transformed in an electrical circuit. Simply put, it is a measure of how much energy is used in a span of time.
Symbol 
P 
SI Unit 
Watt, joule per second 
Scalar or Vector 
Scalar Quantity 
Formula 
P=VI 
Electric Power Formula
The formula for electric power is given by

where,
P is the power
V is the potential difference in the circuit
I is the electric current
Power can also be written as


The above two expressions are got by using Ohms law, Where, Voltage, current and resistance are related by the following relation
Where,

R is the resistance in the circuit.

V is the potential difference in the circuit

I is the electric current
Power Energy Formula
Since power is the rate of energy consumption, energy can directly be calculated using

Where,
E is the energy consumption (in Joules)
t is the time in seconds

Where,
 Q is the charge (in Coulombs)
 V is Potential difference in volts
 t is the time in seconds
Related Physics Concepts
Electric Power Problems
Based on the information given above try the application problem given below:
Examples:
A 9V battery is connected to a resistor having the resistance of 10 Ω. What is the current and power across the resistor?
Solution:
I = V/R = 9/100 = 0.9 A
P = VI = 9 Ã— 0.9 = 8.1 J/s or 8.1 W
Producers and Consumers of Electric Power:
Depending on the function of a component in an electrical circuit, it can be either producers or consumers. A consumer takes in electric energy and transforms it into another type of energy. For example, an electric heater transforms electricity to heat energy. Producers are those that convert some other type of energy to electric energy. For example, in a battery, chemical energy is converted to electricity. Consumers and producers are classified based on whether they consume or produce electric energy.
Practice Questions On Electric Power
Q1: Define electric Power
Ans:electric power measure of the rate of electrical energy transfer by an electric circuit per unit time.
Q2: Write the SI unit of electric power
Ans: The SI unit of electric power is watt
Q3: Write the electric power formula and explain the terms
Ans: The electric power is given by P = VI.
Where V is the potential difference, I is the electric current and P is the electric power.
Q4: Is electric power a scalar quantity or vector quantity?
Ans: Electric power is the scalar quantity
Q5: How can we express power using Ohms law?
Ans: Power formula can be rewritten using Ohms law as P =I2R or P = V2/R.
Where V is the potential difference, I is the electric current, R is the resistance and P is the electric power
Hope you have understood about Electric power, How it is defined, its Symbol, Units, Formula, Terms. For a better understanding of current electricity do read the related articles and answer the practice questions.
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