Question

The approximate value of magnetic field due to a dipole of magnetic moment $1.2{\text{Am}}^2$ at a point $1\text{m}$ away from it in a direction making an angle of ${60}^{\circ }$ with the dipole axis is

• A. $0.8\times {10}^{-7}\text{T}$
• B. $1.6\times {10}^{-7}\text{T}$
• C. $2.4\times {10}^{-7}\text{T}$
• D. $3.2\times {10}^{-7}\text{T}$

Answer 1

The correct option is B $1.6\times {10}^{-7}\text{T}$

The magnitude of the magnetic field at any point due to a dipole of magnetic moment $M$ is

$B=\frac{{\mu }_0}{4\pi }\frac{M}{r^3}\sqrt{1+3{\cos }^2\theta }$

Using the data given in the question,

$B={10}^{-7}\times \frac{1.2}{1^3}\sqrt{1+3{\cos }^2{60}^{\circ }}$

$\therefore B=1.6\times {10}^{-7}\text{T}$

Hence, option $\left(B\right)$ is the correct answer.