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Two short bar magnets each of magnetic m...

Two short bar magnets each of magnetic moment of `9 Am^(-2)` are placed such that one is at `x=-3 cm` and the other at y=-3 cm. If their magnetic moments are directed along positive and negative X-directions respectively, then the resultant magnetic field at the origin is

A

100T

B

10T

C

0.1T

D

0.001T

Text Solution

Verified by Experts

The correct Answer is:
C
At origin, both magnetic fields will be in same direction,

Magnetic field due to `M_(1)` (axial point)
`B_(1) =(mu_(0))/(4pi) xx(2M)/(r^(3))=10^(-7)xx(2xx9)/(27xx10^(-6))`
`B_(1)=(2)/(3)xx10^(-1)T`.
Magnetic field due to `M_(2)` (equatorial point)
`B_(2) =(mu_(0))/(4pi) xx(M)/(r^(3)) =10^(-7)xx(9)/(27xx10^(-6))=(1)/(3) xx 10^(-1) T`
As both `B_(1) and B_(2)` points in same direction, so effective field, `B=((1)/(3)+(2)/(3))xx10^(-1) T`
`rArr" "B=10^(-1) T =0.1 T`
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