User`s guide

20
• the frequency of a vibrating string
• the RPM of the CPO Science Electric Motor or Ripcord Generator
Period Function
The Period Function measures the period of signals which are connected to the
inputs. The photogates can provide the signals (such as with the Pendulum) or the
Sound & Waves experiment can provide the signals. The period is measured in
seconds.
Period Updates Every Other Cycle
You will notice that the period only updates every third time the Pendulum crosses
the light beam. This is because the DataCollector averages over two periods before
updating the display. The averaging technique corrects for errors that occur when
the photogate is not placed at the exact center of the swing.
A Pendulum Crosses Twice Per Cycle
You will also notice that the DataCollector measures the half period of the Pendu-
lum. This is because the pendulum breaks the light beam twice per cycle. The
DataCollector does not know it is “seeing” a pendulum; all it knows is the period
of the breaking of the light beam.
Count Function
The Count Function counts whenever anything breaks the light beam, or sends a
signal. There are two independent counters: A and B. The counters can each count
up to 19,999.