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Exrerimen? Name 71 bt Impedance of Series AC Circuits Objectives: 1, Measure the impedance of a series R-L circuit and the phase between the ac voltage and current and compare your measured values with the calculated values. 2. Measure the impedance of a series R-C circuit and the phase between the ac voltage and current and compare your measured values with the calculated values. 3. Measure the impedance of a series R-L-C circuit and the phase between the ac voltage and current and compare your measured values with the calculated values. 4. Calculate the expected ac rms voltage across each element in a series R-L-C circuit and compare your calculated voltages with the measured values. 5. Demonstrate how Kirchhoff’s voltage law applies to a series ac impedance using phasors. 6. Demonstrate the effect of frequency changes on the ac rms current and voltages in a series R-L-C circuit. * Materials: One dual-trace oscilloscope One function generator One 0-10 mA ac milliammeter Four 0-10 V ac voltmeters One 0.1 uF capacitor One 100 mH inductor One 1 kQ resistor Theory: Complete Experiments 19 and 20 on inductive and capacitive reactance before attempting this experiment. When an ac sinusoidal voltage is applied across a series R-L, R-C, or R-L-C circuit, as shown in Figures 21-1, 21-2, and 21-3, there is an opposition to the ac current flow called impedance (Z), and its unit of measurement is the ohm (©). The voltage across each element and the current in each element are also sinusoidal and have the same frequency as the applied voltage. However, the ac voltage across the inductor will lead the ac current by 90 degrees, the ac voltage across the capacitor will lag the ac current by 90 degrees, and the ac voltage across the resistor will be in-phase with the ac current. This will cause a phase difference (8) between the ac voltage applied to the circuit and the ac circuit current. This phase difference can be between 0 degrees and 90 degrees, depending on the relationship between the total reactance and total resistance in the circuit. 141 
