1 volt
Means 1 joule of potential energy per coulomb of charge.
Electricity · Energy & power
How does charge
do useful work?
The charges are not fuel that gets used up. A source creates an electric field, the field transfers energy through the circuit, and devices convert that energy into light, heat, sound, or motion.
01 · Follow the energy
The field delivers energy.
The charges participate.
Click through one complete energy journey. Notice that the electrons already in each wire move locally—the same electron does not have to race from the battery to the bulb.
Inside a battery, chemical reactions do work to separate positive and negative charge. That stored separation is electrical potential energy—like lifting a weight before letting it fall.
02 · Energy per charge
Voltage tells each coulomb
how much energy is available.
1 ampere
Means 1 coulomb of charge passes a point each second.
1 watt
Means 1 joule of energy is transferred each second.
Put them together
If every coulomb carries V joules and I coulombs arrive each second, then energy arrives at V × I joules per second. That is why P = V × I.
03 · Power versus energy
Power is a rate.
Energy accumulates over time.
A powerful device transfers energy quickly. How much total energy it uses also depends on how long it runs.
Energy-use calculator
A 60 W device running for 4 hours transfers 864,000 joules of energy.
Energy = power × time04 · What the device does
Electrical energy changes form.
Light & heat
In a lamp, charges transfer energy to atoms and electrons in the material, producing radiation and thermal motion.
Motion
In a motor, current and magnetic fields create forces that turn electrical energy into mechanical work.
Stored energy
A battery being charged converts incoming electrical energy back into chemical potential energy.
Path checkpoint
You now have the core story.
Charge creates fields. Voltage describes energy per charge. Current is charge flow. Power is the rate the field delivers energy.
Return to the electricity path →