Physics4BL 2

# Physics4BL 2 - Brian Sek April 30, 2009 Physics 4BL, Lab 7...

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Brian Sek April 30, 2009 Physics 4BL, Lab 7 Lab Partner: Morgan Fryar DC and AC Circuits Introduction The purpose of the experiment is to examine the direct current (DC) and alternating current (AC) circuits. The objective of the DC circuit experiment is to verify Ohm’s Law for the current-voltage relationship by measuring the IV curve across an unknown resistor, and to show deviation from Ohm’s Law for current- voltage through a diode by measuring the IV curve of in the presence of a diode. The value of the unknown resistor R and slope of the IV diode graph will be obtained by linear regression. The objective of the AC circuit experiment is to measure the voltage across the reactive component during the transient period for resistor-capacitor (RC) and resistor-inductor (RL) circuits. The time scales of the transient are to be determined through linear regression as well. Lastly, a resonant RLC circuit is constructed to measure the performance of the circuit from its peak-to-peak amplitudes, as a function of frequency. The experimental and theoretical values of resonant frequency will be compared. The quality factor- sharpness of the resonant peak is calculated using resonant frequency and the curve. Experimental Results Part 1: Ohm’s Law The first experiment consists of two resistors linked in series in a circuit. Measure the resistance of each resistor (R should be approximately 1000Ω and r should be approximately 100Ω) using the voltmeter. Wire the circuit as directed, with the two resistors linked in series. Make sure that the positive and negative terminals are also connected to ground in order to establish a zero point. Open the Physics 4BL program and use the channel CH1 vs. CH0, sampling rate at 1000 samples/sec, and sample size at 10,000 points. Take one sample of data, which should generate a straight line on the screen. The second experiment analyzes the same circuit as the first experiment, but with a diode in the place of R. The rest of the procedure is essentially identical to that of the first experiment. Diagram 1 Table 1

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Resistance ± uncertainty (Ω) R 995 ± 0.005 r 99.4 ± 0.005 Figure 1 Ohm’s law states that V=IR. So, if we plot V vs. I, we expect the plot to be linear, and indeed, Figure 1 does show that the voltage is directly proportional to current. The measured resistance can be found by
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## This note was uploaded on 11/12/2010 for the course PHYSICS 4B 318017201 taught by Professor Carter during the Spring '10 term at UCLA.

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Physics4BL 2 - Brian Sek April 30, 2009 Physics 4BL, Lab 7...

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