Smartphones and the Acoustic Doppler Effect in High School

Experiments using smartphones allow for teaching physics concepts in a fun and engaging way and including interdisciplinary approaches. The exploratory character of the experimental activities, along with the smartphones’ embedded technologies, when applied in the high school classroom, also has the potential to awake the students’ intrinsic motivation, contributing to more meaningful learning. Here, using two smartphones running free apps and a personal computer for data analysis, we present an experiment proposal to quantitatively study the acoustic Doppler effect in secondary schools. One of the smartphones acts as the sound source (SS) emitting a wave signal in a frequency range audible to the human being. The other one acts as the sound receiver (SR). We measured the Doppler frequency due to the relative movement between the smartphones and got good results with this frequency deviating about 1% from that one emitted by SS. This amount is large enough to be detected by SR and allows the teacher, quantitatively, to explain the physical phenomenon to the students.