Circuit Construction Lab Activity

Introduction

In this lab, you will use the PhET Circuit Construction Kit simulation to build and analyze simple circuits. You will learn how to measure voltage and current (amperage) in different circuit configurations while exploring the relationship between circuit components.

Simulation Link: PhET Circuit Construction Kit

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Materials (in simulation)

• Wires
• Battery (DC voltage source)
• AC voltage source
• Light bulbs
• Resistors
• Capacitors
• Switches
• Ammeter (for measuring current)
• Voltmeter (for measuring voltage)

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Safety Guidelines

• This is a computer simulation, so there is no risk of electrical shock.
• In real circuits, always follow proper safety precautions.
• Document your findings carefully.

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Part 1: Simple DC Circuits

Activity 1.1: Building a Basic Circuit

1. Open the simulation and clear the workspace if needed.
2. Drag a battery (9V) onto the workspace.
3. Connect wires to both terminals of the battery.
4. Add a light bulb and connect it to complete the circuit.
5. Observe what happens to the light bulb.

Questions:

• Is the circuit complete? How do you know?
• What direction do you think the electrons are flowing?

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Activity 1.2: Measuring Current

1. Using the same circuit from Activity 1.1, add an ammeter in series with the light bulb.
   • To add the ammeter, break the circuit at one point and insert the ammeter.
2. Record the current reading: _______ A
3. Replace the light bulb with a resistor (10 Ω).
4. Record the new current reading: _______ A

Questions:

• How did changing from a light bulb to a resistor affect the current?
• What do you think would happen if you used a 100 Ω resistor instead?
• Try it and record your observation: _______ A

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Activity 1.3: Measuring Voltage

1. Build a new circuit with a battery and two resistors (10 Ω each) in series.
2. Use the voltmeter to measure:
   • Voltage across the entire circuit: _______ V
   • Voltage across the first resistor: _______ V
   • Voltage across the second resistor: _______ V

Questions:

• How do the individual voltage measurements compare to the total voltage?
• Can you formulate a rule about voltage in series circuits?

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Part 2: Switches and Parallel Circuits

Activity 2.1: Adding a Switch

1. Build a circuit with a battery, a light bulb, and a switch.
2. Test the switch by clicking on it to open and close the circuit.

Questions:

• What happens when the switch is open?
• What happens when the switch is closed?
• In a real-world application, what is the purpose of a switch?

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Activity 2.2: Parallel vs. Series

1. Build a circuit with a battery and two light bulbs in series.
   • Observe the brightness of the bulbs.
2. Rebuild the circuit with the two light bulbs in parallel.
   • Observe the brightness again.
3. Use the ammeter to measure:
   • Current in the series circuit: _______ A
   • Current through each branch in the parallel circuit: _______ A

Questions:

• How does the brightness compare between the two configurations?
• What happens to the current in parallel circuits compared to series?
• If one bulb burns out in each configuration, would the other still work? Test your hypothesis.

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Part 3: AC Circuits and Capacitors

Activity 3.1: AC Voltage Source

1. Remove all components and build a new circuit with:
   • An AC voltage source (set to default values)
   • A light bulb
2. Observe what happens to the light bulb.

Questions:

• How does the light bulb behave differently with AC compared to DC?
• Why do you think this happens?

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Activity 3.2: Capacitors

1. Build a DC circuit with a battery, a switch, and a capacitor.
2. Close the switch and observe for a few seconds.
3. Open the switch and observe what happens.

Questions:

• What is the capacitor doing when the switch is closed?
• What happens after the switch is opened?
• How would you describe the function of a capacitor based on this observation?

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Activity 3.3: RC Circuit

1. Build a circuit with:
   • A battery
   • A resistor (100 Ω)
   • A capacitor
   • A switch
2. Close the switch and use the voltmeter to measure voltage across the capacitor over time:
   • Initial voltage: _______ V
   • After 5 seconds: _______ V
   • After 10 seconds: _______ V
3. Open the switch and measure voltage again:
   • Initial voltage: _______ V
   • After 5 seconds: _______ V
   • After 10 seconds: _______ V

Questions:

• How does the voltage across the capacitor change over time when charging?
• How does it change when discharging?
• What do you think would happen if you increased the resistance? Try it!

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Challenge Activities

Challenge 1: Light Switch Circuit

Design a circuit that uses a single switch to control two light bulbs, where:

• When the switch is in position A, only light bulb 1 is on.
• When the switch is in position B, only light bulb 2 is on.

Draw your circuit diagram before building it.

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Challenge 2: Voltage Divider

Create a voltage divider circuit that produces exactly half the battery voltage. Use the voltmeter to verify your design works correctly.

Explain how your circuit works.