# Measuring light with light dependent resistors: an easy approach for optics experiments

## TL;DR

This paper explores using light dependent resistors as low-cost, easy-to-use sensors for optics experiments, demonstrating their effectiveness in measuring reflected, transmitted light, and estimating glass refractive index with reasonable accuracy.

## Contribution

It introduces a simple calibration method for LDRs and validates their use in various optics measurements, offering an accessible alternative for resource-limited educational settings.

## Key findings

- LDR calibration achieves ~5% precision in illuminance measurements.
- LDR measurements verify angular distribution of Lambertian reflectors.
- Estimated glass refractive index averages 1.51, close to expected 1.52.

## Abstract

We entertain the use of light dependent resistors as a viable option as measuring sensors in optics laboratory experiments or classroom demonstrations. The main advantages of theses devices are essentially very low cost, easy handling and commercial availability which can make them interesting for instructors with limited resources. Simple calibration procedures were developed indicating a precision of $\sim 5\% $ for illuminance measurements. Optical experiments were carried out as proof of feasibility for measurements of reflected and transmitted light and its quality results are presented. In particular, the sensor measurements allowed to verify the angular distribution of a Lambertian reflective material, to observe transmitted and reflected specular light on a glass slab as function of the incoming angle of a light beam, and to estimate glass refractive index with values averaging $1.51\pm0.06$ in satisfactory agreement with the expected 1.52 value.