CONCEPT: If the circular loop is CONSIDERED as a magnetic dipole, then the dipole moment is the product of current and area. Therefore, the magnitude of magnetic moment = area × current M = IAWhere M = Magnetic moment of copper coil, I = Current flowing through a loop and A = Area of coilEXPLANATION:If e is the charge on an electron revolving in an orbit of radius r with uniform angular velocity ω, then EQUIVALENT current is\(\Rightarrow I = \frac{charge (e)}{time (T)}\)Where T = the period of revolution of electron\(\Rightarrow T=\frac{2\pi r}{v}\)∴ The equivalent current will be \(\Rightarrow I = \frac{ev}{2\pi r}\)Area of the orbit is\(\Rightarrow A= \pi r^2\)The magnitude of the magnetic moment\(\Rightarrow M = \frac{ev}{2\pi r}\times\pi r^2=\frac{evr}{2}\)Multiply and divide the above equation by m, we GET\(\Rightarrow M=\frac{emvr}{2m} = \frac{evr}{2}\)