# Lab Report On Rc Time Constant

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Lab Report 4 RC Time Constant Physics 262-003 Author: A. Coughran Lab Partners: E. Ortiz, H. Barham Date: 4/5/17 Lab Report 4 A. Coughran 4/5/17 Objective: The objective in Lab 4 is to measure the RC time constant for a capacitor in a series RC circuit with a resistor. This will be accomplished by the analysis of voltage curves across the resistor. Theory: Kirchoff’s Voltage Law states that the voltage sum across a series circuit containing one resistor and a capacitor must be zero. The formula for voltage on a capacitor is defined below in Equation 1, and the formula for voltage on a resistor is defined below in Equation 2. A combination of these equations yields a formula that correctly expresses Kirchoff’s…show more content…
In Logger Pro, the data collection time was set to 3-4 seconds and the sample rate was set to 1000 samples/second. The voltage on the capacitor was tested and then zeroed before beginning data collection. Next, the power supply was unplugged and the supply voltage (V_0) was set to 5V. Data collection was started and graphs of voltage vs. time were collected. The power supply was re-connected to the circuit after about one second after starting the data collection. This small time delay allowed for the charging curve in the graph to be seen visually with more ease and represent accurate data. This same process was repeated 5 total times for several voltage vs. time curves, and the data was saved in Logger Pro for inclusion in the data section after taking curve fits of the data. Data: A graph visually depicting each of the 5 runs of voltage vs. time. A table representing the numerical data of voltage vs. time for each of the 5 runs above. Procedure A represents the theoretical value for the time constant through the use of the formulas in the theory section, while Procedure B represent the experimental value for the time constant by taking the curve fit of the collected data. Analysis: Procedure A The time the voltage was applied, the time at which the switch was closed, and the time at which the voltage reached one-half of its maximum value after switch closure were calculated for each of the 5 runs above. Using this experimental data, the time