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Resistance is Futile (student handout continued)
Read the procedures below and prepare the data tables needed for parts 1 and 2. Determine what measurements are to
be collected and how many are to be collected to figure out how your data tables should be configured.
Experiment Process/Data Acquisition
Part 1: Constant Conductor Length/ Variable Voltage
1. Connect the clip leads from the ammeter and knife switch to the ends of the pencil lead under investigation. Measure and
record the distance between the clip leads on the pencil lead.
2. Plug in or turn on the power supply. Close the knife switch to the circuit and adjust the voltage till it reads about 0.5 V
on the voltmeter. Record the voltage and current values after the volt meter and ammeter displays have stabilized and then
open the knife switch. Do not leave the switch closed for more than 15 seconds, as the lead heating will negatively
affect experiment results.
3. Repeat the above step, by increasing the power supply voltage in 0.5 V increments until you have gotten to a total voltage
of 5.0 V (10 measurements total)
Part 2: Constant Voltage/ Variable Conductor Length
1. Connect the clip leads from the ammeter and knife switch to the ends of the pencil lead under investigation. Measure and
record the distance between the clip leads on the pencil lead.
2. Plug in or turn on the power supply. Close the knife switch to the circuit and adjust the voltage till it reads about 3.0 V
on the voltmeter. Record the voltage and current values after the voltmeter and ammeter displays have stabilized and then
open the knife switch. Do not leave the switch closed for more than 15 seconds, as the lead heating will negatively
affect experiment results!
3. Move the clip leads so that they are 1 cm closer together and measure the new separation distance between the clips.
Close the knife switch and again measure the voltage and current readings on the meters.
4. Repeat the above step until you have collected about 10 measurements of separation distance, voltage and current.
