LEDs & Solar Cells

Light in, light out

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• LED: photon energy ≈ band gap; $\lambda(\text{nm}) \approx 1240 / E(\text{eV})$.
• Bigger gaps give bluer light. Blue LEDs enabled white LED lighting.
• An LED’s light is nearly one colour, because every photon crosses the same gap.

Steps

1. Light from a junction
2. Design a green LED
3. A TV remote
4. A blue LED
5. Powering an LED
6. One pure colour