# Define the following terms: i) Magnetic flux density, ii) Reluctance, iii) Magneto-motive force, iv) Permeance.

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Define the following terms: i) Magnetic flux density, ii) Reluctance, iii) Magneto-motive force, iv) Permeance.

(i) Magnetic flux density (B): It is the magnetic flux per unit area measured at right angles to the flux path. (Its unit is weber/m2 or tesla).

(ii) Reluctance: It is the opposition offered by magnetic path to flux. It is measured in AT/wb.

(iii) Magnetic Motive Force (MMF): It is defined as the entity (quantity or force) that sets up or creates magnetic flux in a magnetic circuit. It is the product of the number of turns and the current in the coil (MMF = NI). Its unit is Ampere (A) OR ampere-turns

(iv) Permeance: It is the property of magnetic circuit due to which it permits the magnetic flux to set up through it and it is reciprocal of reluctance. Permeance = 1/ Reluctance. Unit: weber/ampere.

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