Tuning a Radio

Electrical resonance

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

• An $LC$ circuit resonates at $f = 1/(2\pi\sqrt{LC})$.
• Radios select one station by resonance.
• $f \propto 1/\sqrt{C}$: a bigger capacitor gives a lower frequency.

Steps

1. An electrical swing
2. Find the station
3. How sharp should it be?
4. Tuning to FM
5. A tiny circuit
6. Quadruple the capacitor