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The electrical equivalent of reluctance is?

Resistance

Inductance

Capacitance

Conductance

Correct Answer

⚙️ TE • Technical Concept & PrincipleElectricalMachine

Option A

Resistance

Quick Summary:

Reluctance is the property of a magnetic circuit that opposes the creation of magnetic flux, making it the exact magnetic analogue of electrical resistance, which opposes the flow of electric current. In a magnetic circuit, Magnetomotive Force (MMF) drives flux through reluctance, just as Electromotive Force (EMF) drives current through resistance in an electrical circuit.

⚙️TETechnical SolutionConcept & Principle

💡 Explanation

🔢 Key Formulas

$S = \frac{l}{\mu A} = \frac{l}{\mu_0 \mu_r A}$ — Reluctance formula in magnetic circuits

$R = \frac{\rho l}{A} = \frac{l}{\sigma A}$ — Resistance formula in electric circuits

$\text{MMF} = \Phi \times S$ — Hopkinson's Law (analogous to $V = I \times R$ )

⚙️ Working Principle

When a magnetomotive force (MMF = $N I$ ) is applied across a magnetic material, it establishes magnetic flux ( $\Phi$ ). The opposition offered by the material to this flux density depend upon its length, cross-sectional area, and magnetic permeability, governed by Hopkinson's Law ( $S = \frac{\text{MMF}}{\Phi}$ ).

📌 Key Points

▸
Reluctance is inversely proportional to permeability ( $\mu$ ), just as resistance is inversely proportional to conductivity ( $\sigma$ ).
▸
The SI unit of reluctance is Ampere-turns per Weber ( $\text{At/Wb}$ ) or $\text{Henry}^{-1}$ ( $\text{H}^{-1}$ ).
▸
Permeance ( $\mathcal{P}$ ) is the reciprocal of reluctance, which corresponds to conductance ( $G$ ) in an electrical circuit.

🛠️ Applications / Uses

▸
Designing magnetic paths in transformers, electric motors, and generators.
▸
Calculating magnetic flux leakage and fringing effects in air gaps.

🔄 Comparison Table

Feature	Electric Circuit	Magnetic Circuit
Driving Force	Electromotive Force (EMF, $V$ )	Magnetomotive Force (MMF, $NI$ )
Flow Quantity	Current ( $I$ )	Magnetic Flux ( $\Phi$ )
Opposing Property	Resistance ( $R = \frac{l}{\sigma A}$ )	Reluctance ( $S = \frac{l}{\mu A}$ )
Reciprocal Property	Conductance ( $G = \frac{1}{R}$ )	Permeance ( $\mathcal{P} = \frac{1}{S}$ )

📄 Additional Information

▸
Option B (Inductance) measures a circuit's ability to store energy in a magnetic field per unit current.
▸
Option C (Capacitance) is the ability to store charge in an electric field per unit voltage.
▸
Option D (Conductance) is the reciprocal of resistance, which corresponds to Permeance in magnetic circuits.

📊 Diagram / Illustration

✅

A is correct — Electrical resistance opposes the flow of electric current just as magnetic reluctance opposes the establishment of magnetic flux.

Core Concepts Used

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Reluctance and Permeance Analogy between Electric and Magnetic Circuits Hopkinson's Law

💡 EXAM TIP

Always remember the basic pair analogies for exams: EMF ↔ MMF, Current ↔ Flux, Resistance ↔ Reluctance, Conductance ↔ Permeance, and Conductivity ↔ Permeability.

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