Circuit with a switch
PARTS AND MATERIALS
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6-volt battery
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Low-voltage incandescent lamp (Radio Shack
catalog # 272-1130 or equivalent)
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Long lengths of wire, 22-gauge or larger
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Household light switch (these are readily
available at any hardware store)
Household light switches are a bargain for
students of basic electricity. They are readily available,
very inexpensive, and almost impossible to damage with
battery power. Do not get "dimmer" switches, just the simple
on-off "toggle" variety used for ordinary household
wall-mounted light controls.
CROSS-REFERENCES
Lessons In Electric Circuits, Volume
1, chapter 1: "Basic Concepts of Electricity"
LEARNING OBJECTIVES
SCHEMATIC DIAGRAM
ILLUSTRATION
INSTRUCTIONS
Build a one-battery, one-switch, one-lamp
circuit as shown in the schematic diagram and in the
illustration. This circuit is most impressive when the wires
are long, as it shows how the switch is able to
control circuit current no matter how physically large the
circuit may be.
Measure voltage across the battery, across
the switch (measure from one screw terminal to another with
the voltmeter), and across the lamp with the switch in both
positions. When the switch is turned off, it is said to be
open, and the lamp will go out just the same as if a
wire were pulled loose from a terminal. As before, any break
in the circuit at any location causes the lamp to
immediately de-energize (darken).
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