What is the formula of the permeance of the strip in the conductor portion?

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Examoogle · Accepted Answer

permeance of the strip = permeability in air * area of the flux path / length of flux path

Explanation: Permeance is the reciprocal of reluctance in a magnetic circuit, quantifying the ease with which magnetic flux is established in a material. It is defined as the ratio of magnetic flux to magnetomotive force, analogous to conductance in an electric circuit. Working Principle: In a magnetic strip of uniform cross-section, the reluctance $S$ is given by $S = \frac{l}{\mu A}$. Since permeance $P$ is defined as the inverse of reluctance ($P = \frac{1}{S}$), substituting the reluctance formula yields $P = \frac{\mu A}{l}$, where $\mu$ is permeability, $A$ is the area, and $l$ is the length of the flux path. Key Formulas: $P = \frac{\mu A}{l}$ — Formula for magnetic permeance; $S = \frac{l}{\mu A}$ — Formula for magnetic reluctance Key Points: Permeance is the magnetic equivalent of electrical conductance ($G = \sigma \frac{A}{l}$); The SI unit for permeance is Henry (H) or Webers per Ampere-turn (Wb/At); Permeance increases with higher permeability and larger cross-sectional area; Permeance decreases as the length of the magnetic path increases Advantages: Simplifies calculation of magnetic flux in series and parallel magnetic circuits; Provides a direct measure of magnetic field efficiency in machine design Disadvantages: Assumes constant permeability, which is inaccurate for ferromagnetic materials due to saturation; Does not account for magnetic leakage flux in complex geometries Applications: Design of electromagnetic actuators and solenoids; Analysis of transformer cores and electrical motor stators; Calculation of magnetic circuit impedance Additional Info: The formula reflects that magnetic flux follows the path of least resistance (reluctance).. Option A suggests a product of all parameters, which is dimensionally inconsistent. Option B is the inverse formula (reluctance). Option D is physically incorrect. Answer: C is correct — Permeance is given by the product of absolute permeability and area divided by the length of the magnetic path. Exam Tip: Remember that magnetic reluctance $S$ is analogous to electrical resistance $R = \frac{\rho l}{A}$. Always verify dimensional consistency: permeance must have the units of Inductance (Henries).

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