Two sound sources with slightly different frequencies produce alternating loud and soft sounds called "beats." The beat frequency equals the difference between the two frequencies.

1. Set up two sound sources (e.g., tuning forks, signal generators, or musical instruments) that produce tones with close but not identical frequencies.
2. Sound them together and listen carefully. Notice the periodic rise and fall in loudness.
3. Adjust one source so that its frequency approaches the other.
4. Observe how the beats become slower as the frequencies get closer.
5. When both frequencies match, the beats disappear, indicating the instruments are in tune.

Beats Demo: Tuning Forks - Physics Demos:

• Use tuning forks of slightly different frequencies (e.g., 256 Hz and 258 Hz).
• Try electronic frequency generators and speakers for precise control.
• Demonstrate with two guitar strings, adjusting tension until the beats vanish.
• Use visualizations (oscilloscope or computer software) to show wave interference patterns.

• Keep sound volumes at safe listening levels to prevent hearing damage.
• Avoid prolonged exposure to loud tones from speakers or instruments.

• Why do beats occur when two close frequencies interfere?
• How does the beat frequency relate to the two original frequencies?
• Why do musicians listen for beats when tuning instruments?
• What happens to the beat frequency as the difference between the two frequencies increases?
• Can beats be observed in other wave phenomena, such as light or radio waves?