A map of electric potential
"A map of electric potential" is a free, interactive Class 12 Physics simulation for NEET and JEE, built on the NCERT section "Equipotential surfaces" in Electrostatic Potential and Capacitance. A potential map with equipotential contours and field arrows for up to three point charges or a dipole, probed point by point. NEET has asked about this idea 6 times in 10 years of papers. JEE Main asked 48 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
From the lesson Equipotential surfaces in Electrostatic Potential and Capacitance. Change the values and watch what happens.
What it shows
NCERT §2.4–2.6
A potential map with equipotential contours and field arrows for up to three point charges or a dipole, probed point by point.
Controls
4 to try
- Dragcharges
- Slidereach charge −5 to +5 × 10⁻⁸ C
- Segmentedpreset pair / dipole / free
- Dragprobe
Try this
With 3 × 10⁻⁸ C and −2 × 10⁻⁸ C 15 cm apart, find both points on their line where V = 0 (9 cm and 45 cm from the positive charge) and read that E ≠ 0 there.
Common mistake
Assuming E = 0 wherever V = 0; adding potentials as vectors.
In NEET
10 years of papers
Asked 6 times in 10 years of NEET.
See the past questions: Electrostatic Potential, Electrostatic Potential and Capacitance (chapter)
In JEE Main
42 shifts analysed
48 questions from Electrostatic Potential and Capacitance across the 42 JEE Main shifts Lumi has analysed (2017–2026).
The idea behind it
NCERT §2.6
- An equipotential surface is one on which V has the same value at every point. Moving a charge along it needs no work.
- The field is everywhere at right angles to the equipotential surface through that point; if it had a component along the surface, moving along it would take work.
- Shapes: concentric spheres around a point charge; planes at right angles to the field in a uniform field; distorted closed surfaces around a dipole or two like charges.
- Field and potential: E = −δV/δl, so the size of E is the drop in potential per unit distance taken at right angles to the equipotentials.
- E points in the direction in which V decreases fastest (the steepest fall of potential).
- Where equipotentials drawn at equal steps of V crowd together the field is strong; where they spread apart it is weak.
- In a uniform field E, two planes a distance d apart along the field differ in potential by Ed.
Questions
5 answers
- What does the "A map of electric potential" simulation show?
- A potential map with equipotential contours and field arrows for up to three point charges or a dipole, probed point by point.
- What mistake does the "A map of electric potential" simulation fix?
- A common mistake it clears up: assuming E = 0 wherever V = 0; adding potentials as vectors.
- Has NEET asked about this idea?
- Yes. NEET has asked about this idea 6 times in 10 years of papers.
- Does JEE Main ask questions from Electrostatic Potential and Capacitance?
- Yes. JEE Main asked 48 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
- Is this simulation free?
- Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Equipotential surfaces" in Electrostatic Potential and Capacitance (Class 12 Physics).
Embed this simulation
Free, with a link back
Teaching this idea? Put the simulation on your own page or LMS with this code.