Question

Two unlike magnetic poles each of pole strength
10 A-m are at 20 cm apart. The resultant
magnetic induction at the mid point on the line
joining them is
1) 1.54 x 10-5 T
2) 2 x 10-4T
3) 15 x 10-4T
4) 15 x 10-6T​

Answer 1

option (b) is correct

The resultant magnetic induction at mid-point is 2 x 10⁻⁴T

Given - pole strength of each unlike magnetic pole = 10A-m

distance between two poles = 20cm = 0.2m

To Find - Magnetic induction at the mid point

Solution-

As both the magnetic poles are of opposite sign the net magnetic induction will be calculated by adding the magnetic induction between pole and mid-point

B(net) = 2 (km/d²) where k =μ0/4π and μ0 = 4π * 10⁻⁷

replace d by d/2 because the distance between one pole and mid-point is half of the whole distance , B(net) will become

B(net) = 8km/d²

putting the values

m = 10A-m

d = 0.2m

B(net) = 8 * 10⁻⁷ * 10/(0.2)²

B(net) = 2 x 10⁻⁴T

The resultant magnetic induction at mid-point is 2 x 10⁻⁴T

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