The period of a pendulum is the time it takes to perform this oscillation, ie, going back and forth.
In theory, this time depends directly on the length of thread and inversely on the acceleration of gravity, by the equation:
where T is the period, l the length of wire and g the acceleration of gravity, equal to .
In this experiment we use an infrared barrier to detect the passage of the thread through a point in his career. You can use any infrared barrier market but on teaching issues, we describe the assembly of that use.