Name
Date
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CASTLE UNIT 5 - ACTIVITY 1
Examine the circuit below and observe the brightness of the bulbs. Draw starbursts on the bulbs
in the circuit below to show the brightness of all bulbs. Draw arrowtails to show the flow rates
causing the observed brightness. Color-code the wires to show the pressure differences that cause
the flow rates.
Explain why you color coded the wires as
you did.
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The wires connecting the bulbs were
originally yellow before the connection was
made to the battery. What might have
caused the pressure of the top right and
bottom right wires to change?
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Focus Question: How is the electric pressure created in wires not directly
connected to the battery?
In your discussion of what caused the pressures in the wires to change, you probably noted that
the process occurred too quickly to observe. Adding a capacitor in parallel to the middle two
bulbs should slow the process down. Before you make the connection, predict the brightness of
the bulbs at the moment of connection. Will all four bulbs light at the same time?
Prediction:
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Bulb
1st
2nd
3rd
4th
1st
2nd
3rd
4th
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Initial
Brightness
Observations:
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Bulb
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Initial
Brightness
©Modeling Workshop Project 2004
1
C5 ACT 1 v3.2
Draw starbursts on the bulbs in the figure below that indicate the initial brightness of each bulb
at the instant of connection. Draw arrow tails that show the directions and rates of flow that
cause the observed brightness. (Don’t forget to include arrow tails for the wires leading to and
from the plates of the capacitor.) Color-code the wires to provide a picture of the pressure
differences that cause these flows.
Which way is most of the charge flowing out of
the junction between the 1st and 2nd bulb?
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From which wire is most of the charge flowing
into the junction between the 3rd and 4th bulb?
Instant of connection
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How does the flow out of the 2nd bulb compare to
the flow into the 3rd bulb?
In the diagram below, use starbursts and
arrowtails to show how the brightness and
flow rates have changed mid-way through the
pressure changes. Color code the circuit.
In the diagram below, use starbursts and
arrowtails to show the brightness and flow
rates ion the final, steady state. Color code
the circuit.
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Conclusion: Write your conclusion on a
separate page.
Consensus: Write your consensus on a
separate page.
©Modeling Workshop Project 2004
2
C5 ACT 1 v3.2