Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
The unit of retentivity is
Ampere turn
Ampere turn/metre
Weber/m2
Weber
Weber/m2
Retentivity (or remanence) is the ability of a magnetic material to retain its magnetization after the external magnetizing force is removed ┬╖ It is measured as the residual magnetic flux density (BrтАЛ) when the magnetic field intensity (H) is reduced to zero in the BтИТH curve of a material.
Retentivity (or remanence) is the ability of a magnetic material to retain its magnetization after the external magnetizing force is removed ┬╖ It is measured as the residual magnetic flux density (BrтАЛ) when the magnetic field intensity (H) is reduced to zero in the BтИТH curve of a material.
BrтАЛ=A╬жrтАЛтАЛ тАФ Where BrтАЛ is retentivity, ╬жrтАЛ is residual flux, and A is the cross-sectional area.
When a ferromagnetic material is subjected to a magnetizing force, the magnetic domains align ┬╖ Upon removing the external force, the internal crystalline structure resists the complete randomization of these domains ┬╖ The remaining flux density, measured in Tesla or Weber/m2, represents the material's 'memory' of the magnetic state.
Retentivity is a property of soft and hard magnetic materials.
Permanent magnets require high retentivity and high coercivity.
Electromagnets (like transformer cores) generally require low retentivity to minimize hysteresis loss.
The unit Weber/m2 is equivalent to the Tesla (T).
Useful for manufacturing permanent magnets.
Enables magnetic data storage technologies.
Causes hysteresis losses in AC applications.
Residual magnetism can interfere with sensitive electronic measurements.
Permanent magnet production
Magnetic recording media
Relays and memory elements
Option B (Ampere turn/metre) is the unit of magnetizing force (H).
Option A (Ampere turn) is the unit of magnetomotive force (MMF).
Option D (Weber) is the unit of magnetic flux (╬ж).
C is correct тАФ Retentivity is a measure of residual magnetic flux density, which is defined as flux per unit area, expressed in Weber/m2 or Tesla.
Always distinguish between magnetizing force (H, unit: AT/m) and magnetic flux density (B, unit: T or Wb/m2) ┬╖ In the BтИТH loop, the intercept on the B-axis is retentivity, while the intercept on the H-axis is coercivity.