EET-117_LAB_8_F21_copy

School Of Engineering Technology and Applied Science (SETAS) Advanced Manufacturing and Automation Technology (AMAT) EET 117 – Lab Instructions Section : __________________ Date: Lab #8 GROUP : ___________________ Series-Parallel Circuits Based on Experiments in Basic Circuits by David Buchla Name : __________ Name :______________________________ Status and Signature : Objectives: 1. Use the concept of equivalent circuits to simplify series-parallel circuit analysis. 2. Compute the currents and voltages in a series-parallel combination circuit and verify your computation with circuit measurements. Required Instruments and Components: Power supply DMM (Digital Multi-meter) Breadboard Alligator test leads (from the EET-117 labkit) Resistors: 2.2 kΩ, 4.7 kΩ, 5.6 kΩ, 10.0 kΩ (from the EET-117 labkit)

Procedure 1. Obtain the resistors listed in the Table 1. Measure each resistor and record the measured value in the table. Reminder of steps to measure resistance using lab DMM (reference to the manual): 1. Connect the device under test to the instrument, as shown: 2. Select a resistance measurement function: • Press 2 to select 2-wire ohms. Ω Table 1. Measured and computed resistance values (use 3 significant digits, metric prefixes). Component Listed Value Measured Value Marks R 1 2.2 kΩ 2.193 kOhms /1 R 2 4.7 kΩ 4.63 kOhms /1 R 3 5.6 kΩ 5.614 kOhms /1 R 4 10.0 kΩ 9.969 kOhms /1 Total: /4 2. Connect the circuit shown in Figure 1. Notice that the identical current is through R 1 , and R 4 so we know that they are in series. R 2 has both ends connected directly to R 3 so these resistors are in parallel. Fig. 1 3. You can begin solving for the currents and voltages in the circuit by replacing resistors that are either in series or in parallel with an equivalent resistor. In this case, begin by replacing R 2 and R 3 with one equivalent resistor. Label the equivalent resistor R 23 . Draw the equivalent series circuit in the space provided below. Show the value of all components, including R 23.

R(2)(3) = (4.7 kOhms)(5.6 kOhms)/4.7 kOhms + 5.6 kOhms R(2)(3) = 2.56 kOhms Marks: / 10 4. The equivalent circuit you drew above (in step 3) is a series circuit. Compute the total resistance R T , total current I T , Voltages on different parts of this equivalent circuit ( V 1 , V 23 , V 4 ) and enter it in Table 2. Reference sub-steps: a) Find the total current, I T , in the circuit by substituting the total voltage and the total resistance into Ohm's law. Enter the computed total current. b) In the equivalent series circuit, the total current is through R 1 , R 23 , and R 4 . c) The voltage drop across each of these resistors can be found by applying Ohm's law to each resistor. Compute V 1 , V 23 , and V 4 using this method. d) Use V 23 and Ohm's law to compute the current in R 2 and R 3 (I 2 and I 3 ) of the original circuit. As a check, verify that the computed sum of I 2 and I 3 is equal to the computed total current. 5. Measure, enter and compare values in the column beside of Table 2. Important reminder: don’t forget to disconnect the power supply when measuring the total resistance. When measuring current always connect ammeter in series and select appropriate connections on DMM. Table 2. Measured and computed values (use 3 significant digits, metric prefixes). Computed (Ohm’s Law) Measured Marks V s 12.0 V 11.962 V /2 R T 14.76 14.58 /4 I T 0.813 mA 0.829 mA /4 V 1 1.79V 1.81V /4 V 23 2.08V 2.1V /4 V 4 8.13V 8.19V /4 I 2 0.44 mA /2 I 3 0.37 mA /2 Total: /26 6. The voltage divider rule can be applied directly to the equivalent series circuit to find the voltages across R 1 , R 23 , and R 4 . Find V 1 , V 23 , and V 4 using the voltage divider rule. Tabulate the results in Table 2 and place results in Table 3.