1. Lab I Recap Lab II Preliminary Dr. Len Trombetta 1 ECE 2100

2. Lab I: Accuracy, Precision, and Significant Figures The number of sig figs shows your measurement resolution. – Sig figs is based on the “first doubtful digit” – Use rules for multiplication, division, addition, subtraction – Constants ( , e …) and calculated values have “infinite” precision (as many sig figs as you need). – In reporting results, use sig figs consistent with measurement resolution. 2

3. Lab I: Percent Error We discussed percent error: – How much error should you expect? – Based on the resistor tolerance, what is the expected max and min error – We are assuming that the meter and power supply are not contributing significant error. 3

4. Lab II: KVL and KCL We will build two circuits and measure several KVL’s and KCL’s. – Is the meter having an effect here? What is the meter resistance? When is meter resistance important? Is the measurement near the resolution of the instrument? 4 http://www0.egr.uh.edu/courses/ece/ece2100/NERD/MeterResistance.pdf

5. Lab II: Percent Error 5 In Lab I we defined error as: In Lab II, the reference value will be the sum of the voltages around a closed loop, and the sum of the currents at a node. So we will need a new definition of error: average voltage in the loop reference

6. Error Bars 6 One other item…error bars: A convenient statement of error can be made like this: v OUT = 5.23 +/- 0.03 [V] This makes it clear that the doubtful digit is doubtful by 0.03 [V].

7. Error Bars 7 with filter: v OUT = 310 +/- 20 [mV] without filter: v OUT = 240 +/- 20 [mV] Output Voltage [mV]

8. Error Bars 8 with filter: v OUT = 310 +/- 50 [mV] without filter: v OUT = 240 +/- 50 [mV] Output Voltage [mV]