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9.
Power Sources and Loads
The experiments use the following power sources and loads.
Power Sources
•
Battery
•
Solar Panel
•
Wind Turbine
•
Fuel Cell
Loads
•
Resistors
•
Capacitor
•
Motor – Propeller
•
Fuel Cell (a fuel cell can be both a power source and a load)
What is a Power Source?
For these experiments a power source is a device that produces both electrical voltage and
current (in effect, power). The power sources use chemical energy (battery, solar panel),
magnetic energy (wind turbine) or hydrogen (fuel cell) to generate voltage and current.
The equation for power is shown below:
P = E*I
What is a Load?
A load is a device that accepts the power coming from a power source and (may) use the power
to do work, like spin a motor. Other loads like resistors and capacitors serve to dissipate or store
power (respectively). In all cases, loads are used to both consume and regulate the power being
produced.
Generally speaking, a load is measured as resistance whose units are in ohms.
In relative terms, a "light" load has a "large" resistance and a "heavy" load has a "small"
resistance. This may be counter intuitive, but it is the case, nevertheless. For example, a 100
ohm resistor presents a "lighter" load to a circuit as compared with a 10 ohm resistor.
The equation for computing the association among voltage, current and resistance (load) is as
follows:
E = I*R
Where P = Power in watts
E = Voltage in volts
I = Current in amps
Where E = Voltage in volts
I = Current in amps
R = Resistance in ohms
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