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Fill in the blank: The phenomenon in magnetic materials where the magnetic flux density lags behind the magnetizing force is called __________.
Hysteresis
Saturation
Permeability
Reluctance
Hysteresis
Hysteresis is the property of a ferromagnetic material where the magnetic flux density (B) lags behind the applied magnetizing field intensity (H). This phenomenon results in energy loss in the form of heat during every cycle of magnetization and demagnetization.
Hysteresis is the property of a ferromagnetic material where the magnetic flux density (B) lags behind the applied magnetizing field intensity (H). This phenomenon results in energy loss in the form of heat during every cycle of magnetization and demagnetization.
WhтАЛ=тИоHтЛЕdB тАФ represents the energy loss per unit volume per cycle, which is equal to the area of the B-H loop.
PhтАЛ=╬╖тЛЕfтЛЕBmaxxтАЛ тАФ Steinmetz formula for hysteresis power loss where f is frequency and BmaxтАЛ is maximum flux density.
As the magnetizing force H is applied and then removed, the magnetic domains within the material do not immediately return to their original unmagnetized state due to internal friction between molecular magnets. This persistence of magnetization when the external field is removed is called retentivity, and it necessitates a negative coercive force to nullify the magnetism.
The area of the B-H loop is directly proportional to the energy loss per cycle.
Hard magnetic materials have a wide hysteresis loop, while soft magnetic materials have a narrow loop.
Hysteresis loss is a significant component of iron loss in transformers and electrical machines.
Necessary for permanent magnet applications (high coercivity).
Used in magnetic memory storage devices.
Causes unwanted heating in transformer cores.
Reduces the efficiency of electrical machines.
Transformer core material selection.
Permanent magnet manufacturing.
Magnetic recording media.
Saturation (Option B) refers to the state where the magnetic flux density reaches a maximum value and cannot increase further despite increasing H.
Permeability (Option C) is the ability of a material to support the formation of a magnetic field within itself.
Reluctance (Option D) is the opposition offered to the flow of magnetic flux, analogous to resistance in electric circuits.
A is correct тАФ Hysteresis is the technical term for the lag of magnetic flux density behind the magnetizing force in ferromagnetic materials.
Always remember that hysteresis loss is directly proportional to the frequency of the AC supply (PhтАЛтИЭf), making it a critical consideration in high-frequency transformer design.
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