Studying Faraday’s law of induction with a smartphone and personal computer

Here we present an inexpensive proposal to experimentally study Faraday's law of induction. The experiment uses low-cost materials, a computer with a sound card and a smartphone, both running free software. A value proportional to the induced electromotive force is measured with the computer's sound card and the data related to the magnetic field time dynamics is recorded using the smartphone's magnetometer. The analysis of the data is made with an electronic spreadsheet. Our proposal is quite suitable to be carried out with secondary school students or even with introductory undergraduate students and allows one to quantitatively study the linear relation between the induced electromotive force and the magnetic flux time rate.