Using a remote control to determine the infrared absorption coefficient in water

TL;DR

This study introduces a simple, low-cost experiment using a TV remote and a smartphone to measure water's infrared absorption coefficient, demonstrating the Beer Lambert law practically.

Contribution

It presents an accessible experimental method for determining water's infrared absorption coefficient using common household devices.

Findings

Experimental value closely matches literature data.

Demonstrates Beer Lambert law with simple setup.

Validates low-cost approach for optical measurements.

Abstract

In this work, we present a simple and low cost experiment designed to determine the infrared water absorption coefficient. We used a TV remote control as a point source of infrared light. The intensity after passing the light through different heights of a water column is measured with a solar cell connected to a speaker. The recorded signal, captured with a smartphone sound recorder, provides a practical demonstration of the Beer Lambert law. The collected data were fitted to the theoretical model, obtaining a very good agreement between the value of the water absorption coefficient obtained experimentally and that reported in the literature.