In hydrostatics, pressure measurement with U-gauges and their relationship to density is a well-known experiment. Very little is studied or experimented with the dynamics of the movement of a liquid in a U-tube probably due to its theoretical complexity but, after all, it is a simple damped oscillating system. In this paper we present a relatively simple experiment that allows studying in some detail the dynamics of the movement of a liquid in a U-tube when an initial pressure gradient is applied. In order to record the information of the column displacement as a function of time we have developed a position sensor system based on a solar cell that allows the recording of the experiment using a simple data acquisition system.

Charging a capacitor with a photovoltaic module is an experiment which reveals a lot about the modules characteristics. It is customary to represent these characteristics with an equivalent circuit whose elements represent its physical parameters. The behavior of a photovoltaic module is very similar to that of a single cell but the electric energy involved is much higher, which represents a major challenge for their characterization. In this work, an experiment is conducted to test out this behavior and in addition to obtain the module I-V characteristic curve. The experiment is simple and only common instrumentation is required.

A couple of experiments analyzing the vibration of bars in different configurations using as a vibration sensor an electric guitar pickup are presented. The device is a versatile and easy to operate sensor that can be used in experiments involving the analysis of vibrations in rods and bars of different composition and in different configurations. This technique is presented with two simple experiments: in one, the vibration of a small rod in a cantilever is analyzed, and in another, the longitudinal vibrations of a rod is measured in order to calculate its propagation speed.