(50 pts)
Pre-lab (15 pts) – graded separately
Abstract: (10 pts)
 Clear and concise 2 pts
 Purpose 2pts
 Procedure (brief) 2pts
 Results 2 pts
 Conclusion and implications 2 pts
Part 1: IV of a Resistor and a Light Bulb (20 pts)
Fill in this table for your resistor data (3 pts – existence of data and reasonable uncertainties plus reasonable sig figs, including nominal value)
Voltage (V) Uncertainty _V (V) Current (mA) Uncertainty _ I (mA)
Create a scatter plot of I vs. V for the resistor data and generate a linear least-squares fit of your plot. Attach your plot to this worksheet.
What does the slope represent? (don’t forget units)
Did the result agree with Ohm's law?
Slope = _____________ ± ____________
 Plot 4 pts o Labeled axis 1 pt o Units 1 pt o Data points 1 pt o Fit of data 1 pt
 What does slope represent (1/R) 2 pts
 Does it agree with Ohm’s Law (should be linear so yes) 1 pts
Fill in this table for your light bulb data (3 pts)
Voltage (V) Uncertainty _V (V) Current (mA) Uncertainty _ I (mA)
Create a scatter plot of I vs. V for the light bulb data. Attach your plot to this worksheet. How does it compare with the plot for the resistor?
Plot – 2 pts here (no fit needed -1 pt with fit if not explained) (labeled axis and data)
This plot should not be linear (in terms of comparison with resistor) (1 pts)
Describe the current-voltage characteristics of the resistor studied in Part 1. Is the current zero when the voltage is zero? If not, explain the discrepancy.
The current should be 0 when the voltage is 0 (nothing happening in the circuit). If the data doesn’t show this (from fit having a y-intercept) we have to look at error propagation to explain it. (2 pts)
Compare the I-V plots for the resistor and light bulb. From the “shape” of I-V plot for the light bulb, what can you conclude about the resistance of the light bulb? Does the light bulb appear to be ohmic or non-ohmic? Is the resistance of the light bulb constant? If not, when is it larger or smaller?
Light bulb should be non-ohmic (not linear slope – resistance of the bulb changes). It is larger when slope is smaller (graphing IV not VI curve). 2 pts
Part 3: Kirchhoff’s Loop and Junction Rules (20 pts)
R1 = __________ ± ________ Ω, V1 = __________ ± __________ V, I1 = __________ ± __________ mA
R2 = __________ ± ________ Ω, V2 = __________ ± __________ V, I2 = __________ ± __________ mA
R3 = __________ ± ________ Ω, V3 = __________ ± __________ V, I3 = __________ ± __________ mA
Data above filled in for 8 pts (all numbers given and reasonable)
Based on the uncertainties of the three current measurements, check if the currents satisfy the junction and three loop rules. Please write out the junction and loop rules. How must you take uncertainties into account in verifying the junction rules?
(8pts) Write out all 4 equations (3 loops and 1 junction – 2 pts per equation) Include discussion of uncertainty for each equation
In addition to the uncertainty of the measuring instrument, does the connection of the ammeter or voltmeter to the circuit cause additional uncertainty? If so, are these uncertainties significant? (2 pts) Depends on their actual measurements, but with correct connections
Kirchoff’s rules should work within uncertainties and we don’t have to worry about the measuring devices.
What lessons did you learn from this experiment? How can you apply what you have learned? (2 pts) Answering the question here with something reasonable (related to circuits being around us everywhere)