Question

A permanent magnet in the shape of a thin cylinder of length $50cm$ has intensity of magnetisation ${10^6}A{m^{ - 1}}$. The magnetisation current is
A) $5 \times {10^5}A$
B) $6 \times {10^5}A$
C) $5 \times {10^4}A$
D) $6 \times {10^4}A$

Answer 1

Hint:Magnetisation current is the current used to magnetise or excite a magnetic core. First, convert all the given values into SI units. Using the formula for Intensity of magnetisation, we can easily find the magnetisation current. All the required values are given.

Formulas Used:
Intensity of Magnetisation, $M = \dfrac{{{I_M}}}{l}$
Where, ${I_M}$ is the magnetisation current, $l$ is the length of the magnet.

Complete step by step answer:
First, convert the given values into SI units. We are given length of magnet, $l = 50cm = 0.5m$ and intensity of magnetisation, $M = {10^6}A{m^{ - 1}}$
The formula for intensity of magnetisation gives $M = \dfrac{{{I_M}}}{l}$ Where, ${I_M}$ is the magnetisation current, $l$ is the length of the magnet.
On putting the values, we get ${10^6} = \dfrac{{{I_M}}}{{0.5}}$
$ \Rightarrow {I_M} = {10^6} \times 0.5$
Which gives us ${I_M} = 5 \times {10^5}$. This is the required answer.

Additional Information:
Magnetisation current is that current is required to provide flux within the core. It's two current components:
1. Magnetization current requires to provide the flux within the transformer core.
-It's not sinusoidal due to the magnetic saturation within the transformer core.
-After saturation within the core, minor changes in flux require a great amount of current.
-The basic components of the magnetization current lags the voltage applied to the core by 90 due to purely inductive circuit.

2. The Core Loss current, required to beat hysteresis and eddy current losses
-Core current is non-linear due to the non-linear effect of hysteresis.
-The basic component of the core-losses is within the phase of the applied voltage.

Note:Always convert the given values into SI units otherwise we will get the incorrect answer. Intensity of magnetisation is defined as the magnetic dipole moment developed per unit volume when a magnetic material is subjected to a magnetising field. Make sure the formula used is correct.