Electric Power

Watts, heat and power lines

An interactive lesson with 7 steps, about 6 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Power $P = VI = I^2R = V^2/R$, in watts.
• Parallel bulbs each get the full voltage, so they are brighter than series bulbs.
• High-voltage transmission cuts current, which slashes the I²R losses.

Steps

1. Energy per second
2. Three forms of the power formula
3. Kettle current
4. Heater resistance
5. Brighter in parallel
6. Two bulbs, two ways
7. High-voltage lines