Comparison of Electric and Magnetic Circuit – Interactive

Φ

Electric vs Magnetic Circuit – Interactive Analogy

EMF ↔ MMF • Current ↔ Flux • Resistance ↔ Reluctance • Similarities & Differences

A magnetic circuit behaves very much like an electric circuit: MMF drives flux through reluctance just as EMF drives current through resistance (Φ = F / S like I = V / R). Change the values on either side and watch the matching quantity respond on the other.

📘 How to Use (tap to hide / show)

1. 1Keep Link both circuits ON. A change on one side makes the same % change to the matching quantity on the other side.
2. 2Move any slider: voltage / coil current, length, area, or change the material.
3. 3Watch the circuits: the current dots move faster or slower, and the flux lines become denser or sparser.
4. 4Read What happened? and the comparison table below — values that changed flash yellow.
5. 5Switch the link OFF to explore each circuit on its own.

1

Explore the Two Circuits

Link both circuits ON: matching quantities change together

⚡ Electric Circuit

Battery EMF V

Conductor length l

Cross-section area a

Conductor material resistivity ρ and conductivity σ = 1 / ρ

Resistance R

Current I

🧲 Magnetic Circuit

Number of turns N

Coil current I

Mean core length l

Core area A

Core material sets relative permeability μᵣ

MMF F = N I

Reluctance S

Flux Φ

Flux density B

⚠ B is above about 1.8 T. Real iron saturates here, so μᵣ would fall and the actual flux would be lower. This simple model keeps μᵣ constant.

What happened?

Move a slider or change a material to see how each circuit responds.

2

Similarities – Live Comparison Table

3

Differences Between Electric and Magnetic Circuits

#	Electric circuit	Magnetic circuit
1	Current actually flows (charges move).	Flux does not actually flow; it is only set up in the path. That is why the flux lines in the drawing do not move.
2	Energy is needed continuously to maintain the current (I²R loss as heat).	Energy is needed only to create the flux; no energy is needed to maintain steady (DC) flux. Only AC causes core losses.
3	Conductivity σ stays nearly constant whatever the current (at a fixed temperature).	Permeability μ changes with flux density B because of magnetic saturation, so reluctance is not constant.
4	Good insulators exist, so current stays inside its conductor.	There is no magnetic insulator; some flux always leaks through the air (leakage flux).
5	Opening the circuit (an air gap) stops the current completely.	An air gap does not stop the flux; it only adds a large reluctance.
6	Current density J is limited by heating of the conductor.	Flux density B is limited by saturation of the core (about 1.5–2 T for iron).

Note: μ₀ = 4π × 10⁻⁷ H/m. Resistance R = ρl / a = l / (σa); reluctance S = l / (μ₀μᵣA). The model is ideal: μᵣ is taken as constant and leakage flux is ignored. Material values are typical textbook figures (copper ρ = 1.68 × 10⁻⁸ Ω·m, silicon steel μᵣ ≈ 4000). Animation speed and flux-line density are scaled to show changes clearly, not drawn to scale.