Electric Circuits unit test
A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.
Brightness in series versus parallel
What "in parallel" actually requires
Brightness reasoning
Forgetting the final reciprocal
Energy stored in a capacitor
Kirchhoff's loop rule
Ideal voltmeter
RC time constant
Kirchhoff's junction rule
Electrical power
Where the energy goes
Resistivity versus resistance
Short answer 1. Define or explain: Why ammeters must have low resistance
3 ptsShort answer 2. Define or explain: Kirchhoff junction rule
3 ptsShort answer 3. Define or explain: Capacitor behavior at t = 0 and t = ∞
3 ptsShort answer 4. Define or explain: Kirchhoff sign conventions
3 ptsFree response
10 ptsStudents are asked to determine the resistivity of the material in a long, uniform wire. They have a battery, an ammeter, a voltmeter, a meterstick, and a micrometer. The cross-sectional area of the wire is measured as 8.0 × 10⁻⁸ m². The students cut samples of different lengths, measure the resistance of each, and record the data below. L (m) 0.20 0.40 0.60 0.80 1.00 R (Ω) 1.1 2.2 3.2 4.3 5.4
A(i). Describe how the students could use the ammeter, voltmeter, and battery to measure the resistance of one wire sample. A(ii). Describe one step that would reduce experimental uncertainty.
B(i). Indicate what quantities the students should graph on the horizontal and vertical axes to obtain a straight line usable to determine the resistivity. B(ii). Describe how the resistivity is related to a feature of that graph.
C(i). Describe the axis labels, with units, and the positions of the plotted points. C(ii). Describe the best-fit line.
D. Using the best-fit line described in part C, calculate an experimental value for the resistivity of the wire material.