Fission & Fusion

Reactors and stars

An interactive lesson with 8 steps, about 7 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Fission: heavy nuclei split, releasing neutrons that can sustain a chain reaction.
• Nuclear reactions release millions of times more energy per atom than chemical ones.
• Fusion powers stars. On Earth it needs over 100 million K and is still experimental.

Steps

1. Chain reaction
2. Critical
3. Too small, big enough
4. How fast is a bomb?
5. Energy per fission
6. Fusion: the power of the stars
7. Deuterium plus tritium
8. Hotter than the Sun