- Physics
- Current Electricity
- Electric Power
In physics, electric power measures the rate of electrical energy transfer by an electric circuit per unit of time. Denoted by P and measured using the SI unit of power which is watt or one joule per second. Electric power is commonly supplied by electric batteries and produced by electric generators.
- Electric Power Definition
- Electric Power Formula
- Power-Energy Formula
- Electric Power Problems
- Frequently Asked Questions – FAQs
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 |
Why shouldn’t you touch electrical equipment with wet hands? Find out answer to this question by watching the video.
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 obtained by using Ohm’s 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
\(\begin{array}{l}P=\frac{E}{t}\end{array} \)
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 = 9/10 = 0.9 A
P = VI = 9 × 0.9 = 8.1 J/s or 8.1 W
Watch the video and solve complete NCERT exercise questions in the chapter Electricity Class 10
Frequently Asked Questions – FAQs
Q1
Define electric Power.
Electric power is the rate at which work is done or energy is transferred in an electrical circuit. Simply put, it is a measure of how much energy is used in a span of time.
Q2
Write the SI unit of electric power
The SI unit of electric power is watt.
Q3
Write the electric power formula and explain the terms.
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?
Electric power is scalar quantity.
Q5
How can we express power using Ohm’s law?
The power formula can be rewritten using Ohm’s 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.
Watch the video and solve important questions in the chapter Electricity Class 10
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