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.

Table of Contents: |

## 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 |

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## 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

P = I^{2}R |

P = V^{2}/ R |

The above two expressions are obtained by using Ohm’s law, Where, voltage, current, and resistance are related by the following relation:

**V = IR**

- 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 ฮฉ. What is the current and power across the resistor?**

Solution:

I = V/R = 9/10 = 0.9 A

P = VI = 9 ร 0.9 = 8.1 J/s or 8.1 W

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## Frequently Asked Questions โ 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 Ohmโs law?

^{2}R or P = V

^{2}/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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