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Part I Exercise Key
This exercise provides consistent results regardless of the actual
voltage put to the circuit.
Some will question why the voltage from some power sources that
say they provide 9 volts are not exactly 9 volts. At this point,
don't worry that it isn't exactly 9 volts.
1.
2.
3.
4. (A). A new 9 volt battery will provide between 9.3 volts
to 9.6 volts.
Reasons for differences
-
is it an alkaline or general battery
-
how long has it been on the shelf
(B). A wall adapter rated at 9 volts will provide
one of two voltages.
-
It will be a "regulated" circuit that provides 9 volts almost
exactly.
-
It will be "unregulated" and provide between 9 volts to nearly
13 volts, depending on the amount of strain it is being put under.
5. The voltage used from tpA to tpB should be .7 volts
to .8 volts.
The voltage used across the LED should
be between 1.9 volts to 2.3 volts.
The differences of voltage across
the LED can be caused by
the color of the LED
the brightness of the LED
the size of the LED
If they are the same size
and brightness, then the following generally holds true.
-
the red uses least,
-
the green uses a bit more
-
the yellow uses the most voltage
-
the amount of voltage provided by the power supply
6.
7.
8. |
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