SMARTPHONE BAROMETER SENSOR IN A PHYSICS EXPERIMENT

Over the past years, portable devices have found an increasing use in all the teaching levels of Physics. This is the case of digital cameras, webcams, wiimote and other game console controllers. Digital techniques have been widely used to visualize Physics concepts. By analyzing the recorded video, distances and time intervals can me measured in order to fully determine the trajectory of a moving body. On the other hand, wireless devices (such as the wiimote) have also been applied in Physics teaching. The wiimote has a three axis accelerometer which communicates with the game console using a Bluetooth device. The wiimote gives Physics teachers a low cost way to track the motion in a variety of Physics experiments; however, it is not a common device at the Physics laboratories.

More recently, smartphones have been incorporated into the variety of portable devices in Physics teaching. Smartphones integrate in one device many capabilities which were apart previously. These capabilities may include a camera, a microphone, a speaker, an accelerometer sensor, a magnetic field sensor, an ambient light sensor, a proximity sensor and a thermometer, among others. Higher-end phones have a built-in barometer sensor that can measure atmospheric pressure. Data measured by it is used to determine how high the device is above sea level, which in turn results in improved GPS accuracy.

In this work, we focus on the barometer sensor of the smartphones and its applications to the study of phenomena within the topic of hydrostatic: the pressure due to a liquid column. The pressure a liquid exerts depends on its depth and also depends on the density of the liquid. Introducing the smartphone in an airtight bag, we can easily measure the pressure inside a liquid as a function of depth by making use of the integrated pressure sensor. The experimental results allow to determine the density of the corresponding liquid obtaining a discrepancy with the theoretical values lower than 1%.