Doppler Effect experiment using PhyPhox® application and Pendulum
Sarah Puspitasari, Primaswari Eka Anggraini, Aidha Ratna Fajarini Sidik, Bebeh Wahid Nuryadin*

Department of Physics, UIN Sunan Gunung Djati Bandung

Abstract

This study aims to observe changes in frequency (Doppler effect) due to harmonic oscillation motion (pendulum) using the PhyPhox® application. In general, this experimental device consists of two smartphones as a sound source and detector, and a pendulum (rope @ 2m). First, the sound source (1 kHz) is hung as a load on the pendulum. Whereas the sound detector uses the PhyPhox® application on the second smartphone which is placed statically around the pendulum. Then, the pendulum is distorted and swung with some variation in height (angle), so the pendulum can move at oscillating speed. The observations show that the sound frequency varies due to the Doppler effect, with the detected frequency oscillating between the minimum frequency (fmin) and the maximum (fmax). For the height deviation of the pendulum 20 cm and a base frequency of 1 kHz, it was observed that fmin and fmax were 996,97 Hz and 1003,26 Hz, which showed that the maximum speed of the sound source was ±1,1 m/s. These observations are in accordance with theoretical analysis which estimates the deviation of the pendulum height of 20 cm will produce a maximum velocity for 1 m/s. The development of observing the Doppler effect using the PhyPhox® application and pendulum is expected to be able to facilitate students in understanding the wave phenomena and harmonic oscillation motion.

Keywords: Doppler effect, wave phenomena, harmonic oscillation, PhyPhox® application

Topic: Physics