EET-117 LAB 5 F21

docx

School

Centennial College *

*We aren’t endorsed by this school

Course

117

Subject

Electrical Engineering

Date

Feb 20, 2024

Type

docx

Pages

Uploaded by huzaifa422

Centennial College ELECTRICAL ENGINEERING TECHNICIAN & TECHNOLOGY Course: EET-117 Name Emanuel, Huzaifa, Yassir Student Number Date Lab #5 OHM'S LAW & POWER IN DC CIRCUITS Based on Experiments in Basic Circuits by David Buchla Objectives: 1. Measure and plot the current-voltage relationship for a resistor. 2. Construct a graph of the data from objective 1. 3. Given a graph of current-voltage for a resistor, determine the resistance. 4. Find the power in a resistor using each of the three basic power equations. 5. Indirectly measure the power in a variable resistor at various settings of resistance. 6. Plot the power dissipated as a function of resistance for the variable resistor of objective 5. Required Instruments and Components: DMM (Digital Multi-meter) VOM Power supply Alligator test leads (from the EET-117 labkit) Resistors: 330 Ω, 1.0 kΩ, 1.5 kΩ (from the EET-117 labkit) Potentiometer of any value (from the EET-117 labkit – example: when it is labeled “102” it is – 10x10 2 Ohm or 1 kOhm resistor) Page 1 of 8

Procedure 1. Measure each resistor listed and record the measured value in the Table 1. Table 1. Measured and computed resistance values (3 significant digits, metric prefixes) Component Listed Value Measured Value Marks R 1 330 Ω 0.325k Ω /1 R 2 1.0 kΩ 0.988kΩ /1 R 3 1.5 kΩ 1.4876k Ω /1 Total /3 2. Connect R1 into the circuit shown in Figure 1 . Caution! Current meters can be easily damaged if they are incorrectly connected. Have your instructor check your connections before applying power. Fig. 1 3. Adjust the power supply for a voltage of 2.0 V. Measure the current that is through the resistor and record it in Table 2 . Table 2. Measured current values (3 significant digits, metric prefixes) V s 2.0 V 4.0 V 6.0 V 8.0 V 10.0 V Mark I 6.34 mA 12.9 mA 18.4 mA 24.3 mA 30.6 mA /5 4. Adjust the power supply for 4.0 V and measure the current. Record the current in Table 2 . Continue taking current readings for each of the voltages listed in Table 2 . 5. Replace R1 with R2 and repeat steps 3 and 4. Record the data in Table 3 . Table 3. Measured current values (3 significant digits, metric prefixes) V s 2.0 V 4.0 V 6.0 V 8.0 V 10.0 V Mark I 2.01mA 4.07mA 6.07mA 8.12mA 10.1mA /5 6. Replace R2 with R3 and repeat steps 3 and 4. Record the data in Table 4 . Table 4. Measured current values (3 significant digits, metric prefixes) V s 2.0 V 4.0 V 6.0 V 8.0 V 10.0 V Mark I 1.35mA 2.69mA 4.03mA 5.37mA 6.77mA /5 Page 2 of 8

7. On Plot 1 , graph all three I-V curves using the data from Tables 2, 3, and 4 . Plot the dependent variable (current) on the y-axis and the independent variable (voltage) on the x-axis. Choose a scale for the graph that spreads the data over the entire grid. Label the three resistance curves with the resistor value. TIP : you can use MS Excel to create the graph as was shown in previous Lab Plot 1 Marks: / 10 8. Construct the circuit shown in Figure 2 . The ammeter is connected in series. Have your instructor check your circuit before applying power if you are not sure of your connections . Fig. 2 Page 3 of 8

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

1. Using your DMM, set the power supply voltage to 12.0V. This voltage also appears across R1, (ignoring the very small v oltage drop across the ammeter). Record the voltage and current (in mA) in the top portion of Table 5 . Table 5. Measured and calculated values (3 significant digits, metric prefixes) Measured value of Mark Resistance Voltage Current 0.330kΩ 12 V 36.5mA /3 Computed Power P = IV P= I 2 R P = V 2 /R 438 mW 45.39 mW 436.36 mW /6 Total: /9 2. Using the measured resistance, voltage and current, compute the power dissipated in R1 . Use each of the three forms of the power law and enter your results in the bottom portion of Table 5 . You should find reasonable agreement between the three methods. Determining Power in a Variable Resistance 3. Modify the circuit by removing the ammeter and adding a 1 KΩ potentiometer in series with R1, as shown in Figure 3 . R2 is the 1 KΩ potentiometer (connected as a rheostat). Fig. 3 Connect the center (variable) terminal to one of the outside terminals. Use this and the remaining terminal as a variable resistor . Adjust the potentiometer for 100 Ω. (Always remove the power source when measuring resistance) . 4. Measure the voltage across R1 and the voltage across R2. Enter the measured voltages in Table 6 . As a check, make sure that the sum of V1 plus V2 is equal to 12.0 V. Then compute the power dissipated in R2 using the equation: Page 4 of 8

Table 6. Measured and calculated values (3 significant digits, metric prefixes) Variable Resistance Setting (R 2 ) V 1 (measured) (V) V 2 (measured) (V) Power (W) in R 2 : P 2 = V 2 2 R 2 Mark 100 Ω 9.18 2.85 0.0812 /4 200 Ω 7.29 4.73 0.112 /4 300 Ω 6.22 5.80 0.112 /4 350 Ω 5.79 6.24 0.111 /4 400 Ω 5.37 6.65 0.111 /4 800 Ω 3.46 8.75 0.0957 /4 1 kΩ 2.94 9.08 0.0824 /4 Total: /28 5. Disconnect the power supply and set R2 to the next value shown in Table 6 . Reconnect the power supply and repeat the measurements made in step 12. Continue in this manner for each of the resistance settings shown in Table 6 . 6. Using the data in Table 6 , graph the relationship of the power, P 2 as a function of resistance R 2 on Plot 2 . Since resistance is the independent variable, plot it along the x-axis and plot power along the y-axis. An implied data point can be plotted at the origin because there can be no power dissipated in R 2 without resistance. A smooth curve can then be drawn to the origin. Plot 2 Page 5 of 8

Marks: / 10 Application task with Multisim Using Multisim, connect the circuit for measuring the current thru individual resistors. As shown in Figure 4 , you have only two single-pole, double-throw switches (SPDT). Switches are to be wired in a way that connects only one resistor at a time to the voltage source with Ammeter1 in series. When S1, is in position B, only R1 is in the circuit; when S1 is moved to position A and S2 is in position A, only R3 will be in the circuit; when S2 is now moved to position B, only R2 is in the circuit. Build the described circuit in the Multisim completing the schematic shown in Figure 13 . Page 6 of 8

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Fig.4 Components for the c ircuit to be connected in the Multisim. Start the simulation and record readings in Table 7. Table 7. The current measurements. Use proper units with up to 3 significant digits and metric prefixes. State of Switches Ammeter1 Marks S1 switch in position B 0.12 A /5 S1 switch in position A S2 switch in position B 0.012 A /5 S1 switch in position A S2 switch in position A 1.2 mA /5 Save your File as “EET-117 Lab 5 Fig .4 ” in the Multisim format and submit it with your lab. Marks: /10 Conclusions. The conclusion summarizes the important points of the laboratory work. You must analyze the examples to add emphasis to significant points. You must also include features and/or things you have done /benefits of a particular procedure, instrument, component, or circuit directly related to the experiment . In this lab the resistance for three different resistors were measured using a DMM. The currents for a 0.33k Ω resistor, a 1.0k Ω resistor, and a 1.5k Ω resistor was measured using a DMM. The relationship between a voltage source and the current was graphed for each resistor. Then the power consumed by the 0.33k Ω resistor was calculated and charted down. Next, a potentiometer was wired in series with a Page 7 of 8

0.33k Ω resistor and the voltage across, the potentiometer meter was measured, using a DMM, and charted down.The power consumed by the potentiometer was also calculated. Then the relationship between the potentiometer positioned at different levels and the power consumed was graphed. When positioning the potentiometer, exact values for resistance could not be attained, therefore approximate values close to resistance required was used (I.e; If 100 Ω could not be achieved, a number close to 100 Ω, for example; 101 Ω, was used). All values measured in table 6 are uncertain. This lab has helped us practice to wire components together from a diagram, as well as plotting a relationship between variables. This can be useful for us in an instance where we are given a diagram and are required to construct it, measure values and plot those values onto a graph. Marks: / 20 Rubric-Grading Criteria Ma x. Marks Punctuality 10 Lab Safety 20 Procedure 75 Application task with Multisim 25 Conclusion 20 Neatness, Spelling, Grammar, and Sentence Structure 10 Total: /160 Page 8 of 8