Physics Lab: Resistance is Futile!
(DCP, CE)
Write a lab report including the following:
Research Question: How does the resistance of a conductor (a pencil lead) depend on the length of
the conductor?
Variables:
Independent: length
Dependent: Resistance
Materials:
Ohm-meter, mechanical pencil lead
Procedure:
Use the ohmmeter supplied to measure the resistance of a pencil lead of some easily
handled length. Start with the test leads as close together as possible, and measure
the resistance. Note the uncertainty in the resistance reading (how much does it
fluctuate by? +/- 0.1 ? +/- 0.5 ?). Note also the uncertainty in your length
measurements (+/- 1 cm? +/- 1 mm?). Include these in your data tables and
subsequently on your graphs as error bars. Take several readings at each length.
Data tables:
Include units, labels, uncertainties in both R and L for all data.
Graphs:
Which variable goes on which axis? Include error bars for both R and L. Graph the
data and draw a best fit line, and then a maximum possible slope line and a minimum
possible slope line. Calculate the slopes of each to obtain an average slope and an
uncertainty value. Consult your teacher and old lab/worksheet packets showing
what is required for obtaining a maximum score for the IB DCP criteria.
Conclusion
& Evaluation
Answer the question regarding the relationship between your variables. Does your
graph what might have been expected from your study of current electricity?
Discuss possible errors or uncertainties; explain what you could do to improve your
lab procedure or results in a meaningful way.