Mr. Rogers' AP Physics C: E&M (with IB Physics) Objectives
|Syllabus||1st Quarter||2nd Quarter||3rd Quarter||4th Quarter||IB Objectives|
|3rd Q objectives||small investigations||IB internal assessment||write up specs||IB rubrics|
Physics E&M Investigations
Presentation of the AP Physics content for E&M will be finished some time in Dec. Starting in January a substantial amount of class time will be devoted to performing hands-on physics experiments in order to answer the essential question shown below:
|Essential Question: Do the mathematical models and principles of physics actually work?|
Relavance: Therory needs to be confirmed by experiments.
The investigations selected below are intended to help meet the IB internal assessment standards
Investigation 1: Investigation of shielding
|IB Standard: Rubrics|
|Purpose / Research Question : Can shielding prevent unwanted electric fields from producing noise signals in wires?|
|Instructions: Wrap about 3 feet of unshielded single conductor wire into a
coil about 10 inches in diameter. connect the two ends to an
oscilloscope and place the coil atop a similar sized coil of an
extension cord plugged into the wall. Observe the noise signal
picked up by the single conductor wire.
Wrap an aluminum foil shield around the single conductor wire and connect one end of it to the oscilloscope's ground. Again observe the noise signal.
|Equipment: oscilloscope, 3 ft of unshielded wire, extension cord|
|Data, Calculations: Record your observations.|
|Deliverables (formative / summative assessment): An Excel spread sheet with|
Investigation 2: Investigation of a light bulb's resistance
|IB Standard: Rubrics .|
|Purpose / Research Question: Determine if a a light bulb follow Ohm's Law.|
|Instructions: For a device following Ohm's Law, a plot
of current vs. voltage drop across the device will be linear with a
slope = 1 / R. Regression analysis can give us a curve of best fit for
the data along with an indicator of the fit's quality (R-square).
Residuals analysis can indicate whether a linear fit is or is not
appropriate. If it is not then the device being tested does not follow
Ohm's law. (Note: if you have not taken AP Statistics Mr. Rogers will
assist you with making the statistical analysis.)
|Equipment: 12 volt light bulb, a resistor designed for high power, variable DC power supply, ammeter, multimeter (voltmeter), wires|
|Data, Calculations: See deliverables.|
|Safety: Shorting out the power supply can damage
the unit and burn up wires. Remember, an ideal ammeter has a
resistance = 0. If you connect it across the power supply without
placing the light bulb or resistor in the circuit, the power supply
will be shorted out. Putting excessive current through the resistor
will overheat it and create a burn hazard.
Note: To prevent overheating of the elements in your circuit, turn the power switch off and adjust the voltage knob on the variable power supply to its lowest setting before connecting wires. When ready to start the experiment, turn the power switch on and adjust the voltage up slowly while monitoring the temperature of the circuit.
Limitations: Subjecting the light bulb to more than its
rated voltage will burn it out. Remember, a light bulb glows because
it reaches very high temperatures. If the bulb glows brightly and is
then turned off it will take some time for it to return to its
original temperature. This could affect your results.
Note: TURN THE MULTIMETER OFF WHEN FINISHED! It is battery operated.
|Deliverables (formative / summative assessment): For both the light bulb and resistor: an Excel spread sheet with a scatter graph of current vs voltage with a linear trend line of best fit showing the equation and R-squared values along with a residual plot of the data indicating whether or not the line of best fit is appropriate or not.|
Investigation 3: Analysis of circuits with resistors in parallel and series
|IB Standard: Rubrics|
|Purpose / Research Question: Do the equations for calculating total resistance actually work?|
Be sure to record a drawing of each circuit.
Note: use the color code to select resistors, keeping in mind that you will not be able to measure total resistance if the resistance is too high or too low. However, measure the resistance of each with the multimeter and use this number in your calculations.
Note: TURN THE MULTIMETER OFF WHEN FINISHED! It's battery operated.
|Equipment: multimeter, various resistors, solderless breadboard|
|Data, Calculations: Calculate a total resistance for each circuit configuration and a % difference from the measured value|
|Safety: The wires on resistors as well as the multimeter probes can inflict puncture wound.|
|Deliverables (formative / summative assessment): A Word document with a sketch of the circuits, a data section and a conclusion.|
Investigation 4: Investigation of Kirchoff's Law
|IB Standard: Rubrics|
|Purpose / Research Question: Do the voltage differences around a closed loop in a circuit actually add up to zero?|
|Instructions: Create a circuit with 2 loops in it and at least 3 resistors. Measure the voltage differences around all 3 loops.|
|Equipment: multimeter, various resistors, solderless breadboard, power supply|
|Data, Calculations: Sum of voltage differences around the loops|
|Questions, Conclusions: Answer the research question using the data from the 3 loops.|
|Safety: Be sure the power supply is set to the lowest practical DC voltage. Starting at around 30 volts, a current can be harmful to humans. Hazards can include burns and in the worst case (usually with AC power) can disrupt the electrical activity of the heart leading to unconsciousness and possibly death. Make all connections with the power turned off. Do not touch bare wires or terminals after the power is on. Carefully check your circuit for shorts before turning power on. Shorting out the power supply will at best blow its fuses. in the worst case it will cause a fire.|
|Deliverables (formative / summative assessment): A Word document with the data calculations, and a sketch of the circuit.|
Investigation 5: Measurement of the Speed of Sound
|IB Standard: Rubrics. Solve problems involving the fundamental and higher harmonic modes.|
|Purpose / Research Question: Measure the speed of sound in aluminum using wave equations|
|Instructions:Create a pure sine wave by making an aluminum rod resonate. Measure its frequency using both a frequency and time plot..|
|Equipment: Aluminum rod, meter stick, resin, Android Phones|
|Data, Calculations: frequency from the time plot. Speed of sound in aluminum from 1st harmonic anaylysis..|
|Safety: The sound is very loud and should be experienced for only short durations.|
|Deliverables (formative / summative assessment): calculations as described above.|
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