Capacitor-Aided System for Teaching and Learning Electricity (CASTLE)
STUDENT LEARNING OBJECTIVES
After completing Section 1 each student will be able to:
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Indicate that bulbs will not light if there is a break in a continuous closed loop.
Identify loops in which bulbs will and will not light by inspecting diagrams.
Provide evidence based on compass observations supporting a one-way direction of
flow in a closed loop.
Using words or arrows, describe the direction of conventional charge flow in a circuit.
Define a circuit as an unbroken loop of conductors that forms a continuous
conducting path.
Describe the differences observed when testing conductors and insulators.
Explain how conductors and insulators relate to a “continuous conducting path”.
Trace the conducting path through a light bulb.
After completing Section 2, each student will be able to:
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Identify bulb filaments as parts of circuits that resist charge flow.
Use bulb brightness and compass deflection as indicators of flow rate.
Distinguish flow rate (amount/sec through) from speed (distance/sec traveled).
Use representations to show flow rate and bulb brightness on circuit diagrams.
Explain how adding series/parallel bulbs will raise/lower “overall” resistance.
Describe evidence that connecting wires have much less resistance than bulbs.
After completing Section 3, each student will be able to:
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Draw schematic diagrams of simple circuits.
Identify the parts of a capacitor (two metal plates separated by an insulator).
Draw arrows to indicate direction of charge flow during capacitor charging and
discharging.
Identify the places in a circuit where mobile charge originates.
Describe both a battery and a Genecon as a pump for moving charge in a circuit.
Compare the similarities and differences between an air capacitor and a capacitor in
an electric circuit.
Explain that the Genecon requires an external source of energy for pumping while a
battery contains an internal source of stored chemical energy.
After completing Section 4, each student will be able to:
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Cite evidence that the mobile charge in a capacitor plate can be compressed.
Identify high/low “electric pressure” with compression/depletion of charge.
Cite evidence that a battery creates HIGH and LOW pressure in its terminals.
Explain why electric pressure is uniform in any wire, and in connected wires.
Explain how a battery and wires create a pressure difference that lights a bulb.
Analyze simple circuits by color-coding conducting parts to represent electric
pressure.
After completing Section 5, each student will be able to:
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Explain how electric pressure is raised or lowered in wires not touching a battery.
Explain how the same steady state flow rates become established in series resistors.
Explain how unequal pressure differences arise across unequal resistors.
Explain how adding a parallel branch reduces the overall resistance in a circuit.
Cite evidence that resistance in the circuit can influence pressure difference in battery
terminals.
After completing Section 6, each student will be able to:
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Demonstrate that an instrument labeled “voltmeter” measures electric pressure
differences.
Demonstrate that an instrument labeled “ammeter” measures flow rates of moving
charge.
Identify a voltmeter as having high resistance and an ammeter as having low
resistance.
Measure the resistance of a circuit component using a voltmeter and an ammeter.
Determine whether a resistor ‘obeys Ohm’s Law.
Compare the equivalent resistance of various bulb combinations.
Define power as the rate of energy transfer, calculated as P = ⊗V•I.
Describe the transfer of energy between batteries, resistors and capacitors.
After completing Section 7, each student will be able to:
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Define ‘motor’ and ‘generator’.
Describe the motor effect and the generator effect.
Define magnetic vector.
Define a magnetic field as a pattern of magnetic vectors.
Use the Right Hand Rule for Motors to predict force direction on charge moving
through a field.
Use the Right Hand Rule for Generators to predict flow direction in a wire moved
sideways through a field.
Describe situations with simultaneous occurrence of motor and generator effects.
Explain why it is difficult to crank a generator connected to a very low resistance.
Describe the function of the components necessary to construct a working motor.
After completing Section 8, each student will be able to:
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Cite evidence that insulators as well as conductors contain charge.
Cite evidence for pressure-lowering charge as well as pressure-raising charge.
Explain why charge in insulators does not normally exhibit pressure effects.
Argue that 2 kinds of charge explain how insulators can become conductors.
Cite evidence that negative charge is the kind that’s moving in circuit wires.
Demonstrate that a circuit provides the same observations whether explained by
conventional flow or by electron flow.
Explain how absorption and emission of light energy accompanies ionization of
atoms and the recombination of electrons & ions into new whole atoms. (Optional)
After completing Section 9, each student will be able to:
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Describe what is meant by “electric pressure halos”
Explain why the compressible fluid model does not account for distant action
Clarify that electric pressure is very different from air pressure
Analyze the “conducting island” experiment, citing evidence for the presence of
electrical distant action in circuits
Conduct electrostatics investigations and explain their results
Explain how both conductors and insulators can become polarized in the presence of
external charge
Explain why all excess charge in capacitors is at the surface of the plates. (Optional)
After completing Section 10 each student will be able to:
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Describe the conditions on potential difference and distance to cause a spark to jump
Calculate electric field values from potential difference and distance
Relate electric field strength to the "push" on a charge at a point in space
Relate electric field direction patterns to equipotential halo lines
Relate electric force on a charge to charge value and electric field strength and
direction
Explain polarization of charge in terms of either electric potential or electric field
Relate electric field in a capacitor to energy storage in the capacitor
After completing Section 11, each student will be able to:
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Identify a diode as a one-way conducting device
Describe the roles of electron and hole charge carriers in diodes and transistors
Describe alternating current and the use of a diode to convert it to direct current
Describe the role of electric potential in the operation of a field effect transistor
Use a field effect transistor to detect potential differences in the space outside charged
objects