In physics, an 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 into 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
- 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
\(\begin{array}{l}P=\frac{E}{t}\end{array} \) |
Where,
E is the energy consumption (in Joules)
t is the time in seconds
\(\begin{array}{l}P=\frac{VQ}{t}\end{array} \) |
Where,
- Q is the charge (in Coulombs)
- V is Potential difference in volts
- t is the time in seconds
Related Physics Concepts
| Relation Between Power And Resistance |
| Relation Between Electric Field And Electric Potential |
| Dielectric Properties – Terminology, Mechanism, Applications. |
| Relation Between Ev And Joule |
Electric Power Problems
Based on the information given above try the application problem given below:
Example:
A 9V battery is connected to a resistor having a 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 × 0.9 = 8.1 J/s or 8.1 W
Frequently Asked Questions – FAQs
Define electric Power
Write the SI unit of electric power
Write the electric power formula and explain the terms
Is electric power a scalar quantity or vector quantity?
How can we express power using Ohms law?
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