Materials:
- Tuning fork (with known or desired pitch)
- Stroboscope (a device that emits repetitive flashes of light at adjustable frequencies)
- A wall or surface where you can project the stroboscope's light.
Procedure:
1. Set Up the Stroboscope:
- Place the stroboscope facing a wall or a suitable surface where you can clearly project the light.
- Plug in the stroboscope and turn it on.
2. Adjust the Flash Rate:
- Start with the stroboscope set to its lowest flash rate.
- Gradually increase the flash rate by adjusting the knob or control on the stroboscope.
3. Observe the Tuning Fork:
- Hold the tuning fork close to the stroboscope's light.
- As you increase the flash rate, observe the tines (prongs) of the tuning fork.
4. Look for Synchronization:
- Continue increasing the flash rate until you notice a point where the tines of the tuning fork appear to freeze or move very slowly.
- At this point, the flash rate of the stroboscope is closely synchronized with the natural frequency of the tuning fork.
5. Determine the Pitch:
- Read the value displayed on the stroboscope. This value represents the flash rate in Hertz (Hz) or flashes per second.
- The observed flash rate at the point of synchronization is the same as the frequency or pitch of the tuning fork.
Example:
If the stroboscope's flash rate at the point of synchronization is 440 Hz, then the pitch of the tuning fork is 440 Hz, which corresponds to the note "A" in the standard Western music scale.
Note:
- When the tines of the tuning fork appear to be frozen, it means that the vibration rate of the fork matches the flash rate of the stroboscope.
- Some tuning forks may have multiple frequency modes or overtones. Experiment with different flash rates to identify the fundamental pitch as well as any harmonics.
By synchronizing the flash rate of the stroboscope with the vibration frequency of the tuning fork, you can accurately determine the pitch of the tuning fork.