Question

A couple of moment $1.5\times {10}^{-5}Nm$ is required to keep a magnetic dipole perpendicular to the magnetic field of $6\times {10}^{-4}$ tesla. The magnetic moment of dipole is __.

• A. $2\times {10}^{-2}A{m}^2$
• B. $2.5\times {10}^{-2}A{m}^2$
• C. $1.5\times {10}^{-3}A{m}^2$
• D. $9\times {10}^{-9}Wb/m^2$

Answer 1

The correct option is B $2.5\times {10}^{-2}A{m}^2$

Given:$\tau =1.5\times {10}^{-5},B=6\times {10}^{-4}$

Solution:By using formula

Torque= magnetic moment$\times$ magnetic field$\times sin\theta$

$M=\frac{1.5\times {10}^{-5}}{6\times {10}^{-4}}$ ($\theta ={90}^0$)

$=2.5\times {10}^{-2}$