Download Lesson 3: Learning the Language for DC Circuits

Kreutter/Costello: DC Circuits 2
Learning the Language for DC Circuits
2.1 Circuit Diagrams
A circuit diagram is a representation that uses symbols to show the components in
a circuit and how they are connected:
Part of Circuit
Wire
Sketch
Schematic Symbol
Ammeter (reads
current)
Voltmeter (reads
voltage)
Resistor
Light Bulb
Battery
Ground
Use the symbols to draw a circuit for a battery, a light bulb, and a single wire.
Make sure the diagram represents a circuit that would result in a light bulb
being lit!
Kreutter/Costello: DC Circuits 2
2.2 Vocabulary
Potential Difference (voltage):
Current:
Resistance:
Series Circuit:
Parallel Circuit:
Kreutter/Costello: DC Circuits 2
2.3 We learned that for a light bulb to glow, the two poles of a battery must be
connected to the light bulb with conducting wires. Come up with analogies that
can explain and predict phenomena related to electric circuits.
Parts of the
Create your own analogy
Electric
Circuit
Battery
Connecting
wires
Moving
Electrons
Light bulb,
resistor
Observed properties of
electric circuit
When resistors are in
series (and you don’t
change the voltage),
current goes down.
When resistors are in
parallel (and you don’t
change the voltage),
current goes up.
Observed properties of your own analogy
Kreutter/Costello: DC Circuits 2
2.4 Test your Ideas For each of the following circuits below; predict the brightness of
the bulbs. Identify each circuit as series or parallel. Then, build the circuits using
real materials. Are the results consistent with the predicted outcome? Explain the
results using any of your analogies of electric phenomena.
(a)
(b)
1
1
2
Circuit Prediction
a
b
c
d
e
(c)
(d)
1
2
2
(e)
1
2
3
1
Results
Explanation
Kreutter/Costello: DC Circuits 2
2.5 Reason
(a) Consider the following partial circuit diagrams below, and indicate whether
components between point A and point B are in parallel or in series:
A
A
A
B
A
A
B
B
B
B
Consider the circuit drawn below, including batteries A and B and the three light
bulbs:
1
2
B
A
3
(b) Indicate two sets of components (pieces) that are each connected in series.
(c) Indicate at least one set of components (pieces) that are each connected in
parallel.
2.6 Represent and Reason
(a) Predict how the brightness of the top bulb shown in the
illustration to the right changes when you close switch 1.
1
2
(b) Predict how the brightness of the top bulb changes when you close switch 2 (switch 1
is open).
(c) Rate the brightness of the three bulbs when both of the switches are closed. Explain
your reasoning using any of the analogies.
Kreutter/Costello: DC Circuits 2
(d) Perform the experiment using the Circuit Construction Kit, record your observations,
and compare them to your predictions.