## 12/02/2020

### Law of Magnetizing Force Between Two Magnetic Poles

Laws of Magnetizing Force
• Let us consider that the two magnet poles are placed in a medium.
• The m1 and m2 is magnetic strength of the two poles, r is distance between them and µ is absolute permeability of the surrounding medium. The force ( F ) between them is

( 1 ) Directly proportional to product of their pole strengths
F α m1m2
( 2 ) Inversely proportional to square of distance between two poles
F α ( 1 / r2 )
( 3 ) Inversely proportional to absolute permeability of the surrounding medium
F α ( 1 / µ )
Therefore
F α m1m2 / µr2
F = k m1m2 / µr2
Where k = Constant
The value of k = 1 / 4π in the SI system
F = m1m2 / 4π µr2   ( Where k = 1 / 4π )
F = m1m2 / 4π µ0 µrr2   ( Where µ =  µ0 µr  )
 F = m1m2 / 4π µ0 µrr2 ….… ( 1 )

Unit Magnetic Pole
• Let us consider magnetic pole strength m1 = m2 = m
• Distance between two poles r = 1
• Force between two magnetic pole F = 1 / 4π µ0

Putting above value in the equation ( 1 )
1 / 4π µ0 = m2 / 4π µ0
m2 = 1
m = ± 1
• The unit magnetic pole is defined as the two poles of opposite polarity having same mass which when placed in air with a distance between them is 1 meter, with a force of  1 / 4π µ0 newtons.

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