This is the result of a 3-days course for High School teachers on Physics with Arduino and smartphone at University "La Sapienza" in Rome, Physics Department, in collaboration with the FabLab Fondazione Mondo Digitale.
This work aims to measure the sound speed in air as a temperature function. In particular, is an educational tool to prove the linear approximation in the temperature range of -10°C to 60°C. We measure the sound speed with an ultrasonic sensor, deriving it by the time that sound waves takes to cover a certain distance. This due to a box in which me put the sensor, so we can measure both sound speed and temperature of a quite definite portion of air.
For this work we use:
- Arduino Uno Rev.3
- Ultrasonic sensor HC-SR04
- Temperature sensor TMP36
- Wood box 15x20x10 cm
- Felt
- Dehumidifiers salts
- Hair dryer
I put here the arduino sketch (inside the soudspeed folder), the python script to perform data visualization and a requirements.txt file to install all the necessary python libraries.
We measure the sound speed with the ultrasonic sensor with:
where d is the lenght of the box (i.e. 20 cm) and ts the time for ultrasonic waves to travel the double of that lenght.