Identify the following magnetism of the image given below. And also explain it properly & well...... Plzz
Solution:
The shown curve is called hysterisis curve. It is the curve drawn between and .
The phenomenon in which the magnetic induction (B) lags behind with respect to the magnetizing field H is called hysteresis. It occurs when an external magnetic field is applied to a ferromagnet such as iron and the atomic dipoles align themselves with it. Even when the field is removed, part of the alignment will be retained: the material has become magnetized. Once magnetized, the magnet will stay magnetized indefinitely.
The relation between B and H in ferromagnetic materials is complex. It is often not linear and it depends on the magnetic history of the sample. The given B-H curve depicts the behaviour of the material as we take it through one cycle of magnetisation.
Let the material be unmagnetised initially. We place it in a solenoid and increase the current through the solenoid. The magnetic field in the material rises and saturates as depicted in the curve Oa. This behaviour represents the alignment and merger of domains until no further enhancement is possible. It is pointless to increase the current (and hence the magnetic intensity H ) beyond this. Next, we decrease H and reduce it to zero.
At H = 0, B ≠ 0. This is represented by the curve ab.
The value of B at H = 0 is called retentivity or remanence. The domains are not completely randomised even though the external driving field has been removed.
Next, the current in the solenoid is reversed and slowly increased. Certain domains are flipped until the net field inside stands nullified. This is represented by the curve bc. The value of H at c is called coercivity.
As the reversed current is increased in magnitude, we once again obtain saturation. The curve cd depicts this.
Next, the current is reduced (curve de) and reversed (curve efa). The cycle repeats itself.
It is to be noted that the curve Oa does not retrace itself as H is reduced.
For a given value of H, B is not unique but depends on previous history of the sample. This phenomenon is called hysterisis.
The shown curve is called hysterisis curve. It is the curve drawn between and .
The phenomenon in which the magnetic induction (B) lags behind with respect to the magnetizing field H is called hysteresis. It occurs when an external magnetic field is applied to a ferromagnet such as iron and the atomic dipoles align themselves with it. Even when the field is removed, part of the alignment will be retained: the material has become magnetized. Once magnetized, the magnet will stay magnetized indefinitely.
The relation between B and H in ferromagnetic materials is complex. It is often not linear and it depends on the magnetic history of the sample. The given B-H curve depicts the behaviour of the material as we take it through one cycle of magnetisation.
Let the material be unmagnetised initially. We place it in a solenoid and increase the current through the solenoid. The magnetic field in the material rises and saturates as depicted in the curve Oa. This behaviour represents the alignment and merger of domains until no further enhancement is possible. It is pointless to increase the current (and hence the magnetic intensity H ) beyond this. Next, we decrease H and reduce it to zero.
At H = 0, B ≠ 0. This is represented by the curve ab.
The value of B at H = 0 is called retentivity or remanence. The domains are not completely randomised even though the external driving field has been removed.
Next, the current in the solenoid is reversed and slowly increased. Certain domains are flipped until the net field inside stands nullified. This is represented by the curve bc. The value of H at c is called coercivity.
As the reversed current is increased in magnitude, we once again obtain saturation. The curve cd depicts this.
Next, the current is reduced (curve de) and reversed (curve efa). The cycle repeats itself.
It is to be noted that the curve Oa does not retrace itself as H is reduced.
For a given value of H, B is not unique but depends on previous history of the sample. This phenomenon is called hysterisis.