Author: admin

Purpose

In this lab, you will investigate equipotential lines and their relationship to the electric field. Instead of just reading about voltage and field patterns, you will map them yourself using the PhET Charges and Fields simulation.

Your job is to build charge arrangements, trace lines of equal potential, sketch electric field lines, and estimate the electric field from how quickly the potential changes with distance.

By the end of this lab, you should be able to:

• Explain what an equipotential line means physically.
• Describe how electric field lines relate to equipotential lines.
• Use voltage differences and distance to estimate electric field strength.
• Recognize where the electric field is stronger, weaker, or more uniform from a map.

Simulation Link

Use this simulation for the entire lab:

If the embedded version runs slowly on your device, open it in a new tab using the link above.

Simulation (Embedded)

Setup

1. Open the simulation.
2. Turn off everything except Grid at first.
3. Locate the voltage meter and the ruler.
4. You will use the voltage probe to find points that have the same voltage and then connect those points into equipotential lines.

What You Turn In

Submit ONE PDF. This should be a compact lab packet, not a giant formal report.

Your PDF must include these parts, in this order:

1. Part A: Two Lines map with equipotential lines clearly labeled.
2. Part A field-line sketch drawn on the same map.
3. Part A questions answered in complete sentences, with work shown for the electric field estimate.
4. Part B: Two Circles map with equipotential lines clearly labeled.
5. Part B field-line sketch drawn on the same map.
6. Part B questions answered in complete sentences, with work shown for the electric field estimate.
7. Part C: Random Shape map with equipotential lines clearly labeled.
8. Part C field-line sketch drawn on the same map.
9. Part C questions answered in complete sentences.
10. Final conclusion questions answered clearly.

Important expectations:

• Your maps may be hand-drawn on graph paper or drawn on top of screenshots.
• Your work must be neat and readable.
• Equipotential lines must be labeled with voltage values.
• Electric field lines must include arrows showing direction.
• When you estimate electric field strength, you must show your calculation.
• Submit everything as one single PDF.

What Each Map Must Show

For each of the three setups, your map must include:

• The charge configuration you created
• At least 7 equipotential lines total (the 0.0 V line plus at least 6 others when applicable)
• Voltage labels on the equipotential lines
• 810 electric field lines, drawn so they are perpendicular to the equipotential lines
• Arrowheads on the electric field lines

Think of each page as a clean scientific diagram, not a doodle goblin battlefield.

Part A Two Lines

Build this setup: Make two straight lines of charges about 3 meters apart, one positive and one negative.

Procedure

1. Create two straight charge lines in the simulation, spaced about 3 m apart.
2. Check the voltages near the blue and red charge lines.
3. Use the voltage probe to find points where the voltage is 0.0 V. Mark enough points to trace the full 0.0 V equipotential line.
4. Repeat for at least 6 more equipotential lines at different voltages between the two conductors.
5. Label each equipotential line with its voltage.
6. Draw 810 electric field lines that are everywhere perpendicular to the equipotential lines.

Answer these questions in your PDF:

1. Where do the electric field lines begin and end?
2. Where are the electric field lines closest together? Where are they farthest apart? What does that tell you about field strength?
3. What is the approximate potential midway between the two conductors?
4. What is the approximate electric field strength midway between the two conductors?
   Show your work. Use the voltage difference between two nearby equipotential lines and divide by the distance between them.

Part B Two Circles

Build this setup: Make one positive ring and one negative ring in the simulation.

Procedure

1. Create two circular charge arrangements, one positive and one negative.
2. Map the equipotential lines the same way you did in Part A.
3. Trace and label at least 7 equipotential lines total.
4. Draw 810 electric field lines perpendicular to the equipotential lines.

Answer these questions in your PDF:

1. Where do the electric field lines begin and end?
2. Where are the field lines closest together? Where are they farthest apart? Why?
3. What is the approximate potential midway between the two conductors?
4. What is the approximate electric field strength midway between the two conductors?
   Show your work. You may estimate this using the change in potential over distance near the center, then check with a field sensor.

Part C Random Shape

Build this setup: Make two different random charge shapes.

Procedure

1. Create two different random-shaped charge arrangements.
2. Map the equipotential lines as before.
3. Draw a set of electric field lines on top of your equipotential map.

Answer these questions in your PDF:

1. Where is the electric field strongest? What is its approximate magnitude?
2. Where is the electric field most uniform? How can you tell?

Final Conclusion Questions

Answer these in complete sentences.

1. What changes if you switch which side is red (positive) and which is blue (negative)?
2. If you wanted to push a charge along one of the field lines from one conductor to the other, how does the choice of field line affect the amount of work required?
3. The potential is everywhere the same on an equipotential line. Is the electric field everywhere the same on an electric field line? Explain.

Formatting Rules

• Submit one PDF only.
• Your writing must be readable.
• Your diagrams must be large enough to see clearly.
• Voltage labels must be visible.
• Show calculations for any electric field estimate.
• You may type answers or handwrite them, but the final PDF must be clean and organized.