Table of Contents
Advertisement
Analysis:
The motor presents a relatively heavy load to the fuel cell. This can be seen by observing the
resistance readings below the meter of between 1.60 and 1.70 ohms. This is over 6 times as
much as the 10 ohm load in Experiment #1, which accounts for the rapid decrease in voltage and,
correspondingly, current and power.
Notice that at the very beginning of the plot, when the motor was first connected to the circuit
board, that the voltage, current and power readings were at their maximum. This is indicated by
the spike in the red and blue lines. However, as the voltage decreased, so did the power. This
can be confirmed using the formula below for computing power – when voltage or current
decrease, so does power:
P = E*I
As an exercise, plug in the observable units of voltage and current on the plots to confirm the
formula's validity. For example,
P = E*I
P = 0.063 * 0.054
P = 0.003 watts
If data was being logged, the intermediate voltage, current, resistance and power readings could
also be examined. As such, you are encouraged to re-perform this experiment with the data
logging feature enabled.
Where P = Power in watts
E = Voltage in volts
I = Current in amps
(taken from the meter readings on the last plot)
44
Advertisement
Table of Contents
