Welcome to Proteus Labs, where you will dive into the world of electrical circuits by assembling, measuring, and analyzing a parallel circuit. This lab provides a hands-on opportunity to explore the behavior of parallel circuits and the use of measurement tools like the multimeter. Before starting, familiarize yourself with the equipment and safety guidelines to ensure a successful experiment.
Educational Goals
- Understand the structure and behavior of parallel circuits: Learn how parallel circuits are constructed and how they differ from series circuits in terms of voltage, current, and resistance.
- Master the use of a multimeter: Develop skills in using the multimeter to measure voltage, current, and resistance accurately, both in series and parallel configurations.
- Apply Kirchhoff’s and Ohm’s laws: Use Kirchhoff’s first law and Ohm’s law to analyze the relationships between voltage, current, and resistance in parallel circuits.
- Explore the impact of measurement methods: Understand how multimeter settings (voltage mode vs. current mode) influence the circuit and the measurements taken.
- Develop critical thinking and problem-solving skills: Use reasoning and calculations to troubleshoot circuits, interpret measurement results, and verify theoretical predictions.
- Document and analyze experimental data: Learn to record circuit diagrams, measurements, and calculations systematically to support scientific inquiry and reproducibility.
Protocol
Construction of the circuit
Connect the power supply to the X and Y rows of the test plate.
- Turn on the power supply using the switch and take note of the value displayed on the power supply.
- Take a wire and connect it from row X to location A-10.
- Take a resistor from the bin on your right and connect it from B-10 to B-11.
- Take a resistor from the bin on your right and connect it from C-11 to C-12.
- Take a wire and connect it from B-12 to B-15.
- Take a wire and connect it from E-15 to row Y.
You have built the first branch of your circuit. Since there is only one branch, the circuit is currently in series. A parallel circuit consists of several branches.
- Take a switch and place it on your test board.
- Take a wire and connect it from E-10 to the switch.
- Take a wire and connect it from the switch to E-14.
- Take a resistor from the bin on your right and connect it from D-14 to D-15.
- Make sure the switch is activated. If it is not, the circuit diagram will only display a single branch.
- Save your circuit.
Measure a circuit
During the lab on series circuits, you unknowingly built a parallel circuit! That’s right, you connected your multimeter in parallel with your resistor to measure the voltage. But what would happen if you used the multimeter in series?
To know this, you must understand how a multimeter works. Think of the multimeter as a resistor. When it is set to V mode, its resistance is enormous! Using Kirchhoff’s laws and Ohm’s law, it is possible to prove that adding a huge resistance in parallel does not affect the equivalent resistance of the previous circuit. However, each branch will have the same voltage!
However, if we place this large resistance in series, it will take all the voltage and thus block the rest of the circuit.
How to measure the current? Use the A mode of the multimeter!
In this mode, one can imagine that the resistance is practically zero! Thus, the inverse reasoning of the one above applies. Try to convince yourself of this!
It’s time to explore this new mode of the multimeter.
- Disconnect the switch connectors.
- Take one of the two free connectors and connect it to the central socket (COM) of the multimeter.
- Take the other connector and connect it to the left socket (10A) of the multimeter.
- Make sure the central wheel points toward A.
- You replaced the switch with the multimeter, thus placing the latter in series. The displayed value is the current in the branch.
- Save the diagram of your circuit.
- Try to measure the current at the source yourself.
- Using the current from the branch and the source, apply Kirchhoff’s first law to find the current in the other branch.
- Try to measure the voltage across each resistor in the other branch yourself. To do this, use the multimeter in V mode.
- With the current and voltage of each resistor, you can invoke Ohm’s law and prove that they indeed have the same resistance!
- Send your results
Anticipated Outcomes
Results are found at this link
- Understanding parallel circuit behavior
Participants will observe that voltage across parallel branches remains constant, while the current divides based on resistance. - Accurate multimeter usage
Students will confidently switch between multimeter modes (V and A) to measure voltage and current effectively. - Verification of electrical laws
Using Ohm’s law and Kirchhoff’s laws, participants will confirm that measured values align with theoretical predictions. - Realization of measurement impact
Students will see how multimeter resistance affects circuits in different configurations, gaining insights into proper measurement techniques. - Improved analytical skills
By calculating unknown values and validating results, participants will enhance their critical thinking and problem-solving abilities.
Significance and lessons learned:
- Behavior of parallel circuits
Students learn that voltage remains constant across branches in a parallel circuit, while current divides based on resistance. This understanding is crucial for analyzing and designing electrical systems. - Significance of measurement techniques
Participants gain insights into how multimeter settings (voltage vs. current modes) affect circuit behavior. They understand the impact of introducing resistance in parallel versus series configurations. - Verification of electrical laws
By applying Ohm’s and Kirchhoff’s laws, students see how theoretical principles align with practical observations, reinforcing the relevance of these laws in real-world applications. - Application of critical thinking
Troubleshooting circuit configurations and interpreting measurement data teaches students to think analytically and approach problems systematically. - Understanding the importance of precision
Accurate assembly and measurement are critical in obtaining reliable results. Students learn the value of precision in scientific experiments and its implications for electrical design and troubleshooting. - Collaboration between theory and practice
The lab bridges theoretical knowledge with hands-on experience, helping students appreciate the practical applications of scientific principles. - Skills in data documentation and analysis
Students learn to document observations, save circuit diagrams, and analyze their results systematically, emphasizing the importance of organization and reproducibility in scientific experiments. - This lab instills a strong foundation in electrical principles, practical skills in circuit analysis, and the confidence to tackle more complex problems in physics and engineering.
Summary of Assignment by Grade Range
Grades 6-8 (Middle School)
- Focus: Basic understanding of parallel circuits and the role of components like resistors and switches.
- Activities: Assemble a basic circuit, observe voltage consistency across branches, and explore the use of multimeters.
- Learning Outcomes:
- Recognize the difference between series and parallel circuits.
- Gain confidence in connecting components and measuring voltage.
Grades 9-10 (Junior High School)
- Focus: Intermediate analysis of current and voltage in parallel circuits.
- Activities: Measure and calculate current and voltage in each branch, applying Ohm’s and Kirchhoff’s laws.
- Learning Outcomes:
- Understand how current splits in parallel branches.
- Use multimeters effectively for voltage and current measurements.
Grades 11-12 (High School)
- Focus: Advanced exploration of parallel circuit dynamics and measurement techniques.
- Activities: Analyze the impact of multimeter settings on circuit behavior, calculate resistance using experimental data, and troubleshoot measurement challenges.
- Learning Outcomes:
- Master the application of Ohm’s and Kirchhoff’s laws in complex scenarios.
- Develop precision in data recording and interpretation.
- Gain insights into real-world circuit design and testing challenges.
Laboratory essentials
Instruments
- Multimeter
- Connecting wires
- Resistors
- LEDs
- Light bulbs
- 2-way Switches
- Breadboard
- Power Supply
- Resistor color code chart