Energy delivered by a 5 W phone charger in 2 hours

Answer: energy = 36,000 J (in watt-hours 10 Wh, in kilowatt-hours 0.01 kWh).

What we know

  • Power: 5 W
  • Time: 2 h = 7200 s (converted to the unit the formula takes)

Step by step

Given
P = 5 W, t = 7200 s
Formula
E = P × t
Substitute
E = 5 × 7200
Result
E = 36,000 J

All results

Energy36,000 J
In watt-hours10 Wh
In kilowatt-hours0.01 kWh

Open the watts to joules calculator with these numbers → and change any of them.

The physics

A watt is one joule per second, so energy is simply power multiplied by the time it flows: E = P × t. Run a 60 W bulb for 60 seconds and it consumes 60 × 60 = 3,600 joules. The joule is the SI unit of energy; the watt is the rate at which that energy is delivered or used.