Acoustic testing of the inverse-square law using the infrared signal of a remote control

In this work, the inverse-square law has been tested for the electromagnetic radiation in the infrared range. As a point-source, a TV remote control has been used. The intensities registered by a solar cell plugged to a speaker have been measured acoustically by recording the sound produced by the infrared pulses. The recorded audio is edited to find the intensities for different distances between the remote control and the solar cell. The results were fitted with a parametric function of the intensity inversely proportional to the distance square. A very good agreement was achieved.