Understanding Reciprocal of Reluctance

The question asks to identify the term that represents the reciprocal of magnetic reluctance.

Key Magnetic Concepts

• Reluctance (∂): This is the magnetic analogue of electrical resistance. It measures the opposition a magnetic circuit presents to the establishment of magnetic flux. It is calculated as the ratio of Magnetomotive Force (MMF) to magnetic flux (Φ). Mathematically, ∂ = MMF / Φ.
• Permeance (P): This term describes the ease with which magnetic flux can be established in a material or magnetic circuit. It is defined as the ratio of magnetic flux (Φ) to the Magnetomotive Force (MMF). Mathematically, P = Φ / MMF.

Relationship between Reluctance and Permeance

By comparing the definitions:

• Reluctance: ∂ = MMF / Φ
• Permeance: P = Φ / MMF

It is evident that Permeance (P) is the inverse or reciprocal of Reluctance (∂):

P = 1 / ∂

Evaluating Options

• Permeability: Relates to a material's ability to support magnetic fields, not the direct reciprocal of reluctance.
• Susceptibility: Measures how much a material becomes magnetized in response to an external magnetic field.
• Permeance: Defined precisely as the reciprocal of reluctance.
• Reluctivity: The reciprocal of permeability (ν = 1 / μ), representing opposition per unit dimensions.

Therefore, the correct term that is the reciprocal of reluctance is Permeance.