Question

The force acting on a pole of pole strength $1 \,Am$ is $ {{10}^{-4}}N $ . The magnetic field at that point is:

• A. $ \text{11 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{-4}}}\text{T} $
• B. $ \text{10 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{-4}}}\text{T} $
• C. $ \text{0}\text{.1 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{-4}}}\text{T} $
• D. $ \text{1 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{-4}}}\text{T} $

Answer 1

Answer: (D)

A magnetic charge (pole) placed in a magnetic field experiences a force
$ F=mB $
Here, $ F={{10}^{-4}}N,\,m=1\,Am $
$ \therefore $ $ B=\frac{F}{m}=\frac{{{10}^{-4}}}{1}={{10}^{-4}}T $
Note: The force on positive magnetic charge is along the field and a force on a, negative magnetic charge is opposite to the field.