Energy can change from one form to another but is never destroyed. Power is how fast energy is used.
Power
$P = \frac{E}{t}$ Power (watts) = Energy (joules) ÷ time (seconds)
Example: a device using 100 J in 5 s has a power of $100 \div 5 = 20$ W. A more efficient device wastes less energy.
Remember
- Power = energy ÷ time, measured in watts (W).
- Energy is conserved — it only changes form.