ELECTRIC POWER AND SI UNIT CBSE PHYSICS

 

Electric Power

Electric power is the rate at which electrical energy is converted into another form of energy (such as heat, light, or motion) or the rate at which work is done by an electric current.

Mathematically:

$$\mathrm{<span\; style="font-size:\; medium;"><b>P</b></span>}<span\; style="font-size:\; medium;"><b>=</b></span>\frac{\mathrm{<span\; style="font-size:\; medium;"><b>W</b></span>}}{\mathrm{<span\; style="font-size:\; medium;"><b>t</b></span>}}$$

• $P$ = power (in watts)

• $W$ = work or energy (in joules)

• $t$ = time (in seconds)

For electrical circuits, it can also be expressed as:

P=V×I

Where:

• $V$ = potential difference (in volts)

• $I$ = current (in amperes)

• P=I2R or P=V2/R​

Or, using Ohm’s law:

SI Unit of Electric Power:

• Unit: watt (W)

• Definition: $1\text{watt}=1\text{joule/second}$

• That means if a device consumes 1 joule of energy every second, its power is 1 watt.