Datalogging in Science

To measure the frequency of a tuning fork.

Overview
In this demonstration a tuning fork is set vibrating and a sound sensor connected to a data logger records the sound it makes. (The sound sensor is set to record the sound level in millivolts (mV) rather than decibels). A graph of sound level in mV is plotted against time in milliseconds. The software enables the interval between peaks to be measured accurately and so the frequency of the tuning fork can be calculated.

Theory
Frequency equals the reciprocal of period. f = 1/T
Period is the time between successive peaks.


Apparatus

Procedure

1. Connect the Sound sensor to the data logger and connect the data logger to the computer.

2. Ensure that the Sound sensor is set to record sound level
in mV rather than in decibels (This may be done by using
the Sensor Configuration program).

3. Close the Sensor Configuration program and launch the
Graph program.
Set the datalogger to record in Fast mode (for 1 second at intervals of 1 milli-second).

4. Set the tuning fork vibrating and then begin recording.

5. When recording has finished and the data retrieved (perhaps after 10 seconds) a graph of Sound in mV against time will be displayed.

6. Measure the interval between peaks 10 cycles apart and deduce the period by dividing by ten.

7. Calculate the frequency of the fork by finding the reciprocal of the period.

8. Save the recorded data before analyzing the results.

Results
Measure the frequency a number of times and find an average.

Questions
1. Is the frequency of the sound in air the same as the frequency of the tuning fork? Why?

Extensions
Repeat the demonstration with tuning forks of different frequency.

Data Harvest users

1. Connect the sensor to the datalogger and the logger to the computer
2. Then click the Set Up icon to the right of this message.
3. When the software opens, click the Play button.