A magnetic wire of dipole moment 4π Am2 is bent in the form of semicircle. The new magnetic moment is

Question

A magnetic wire of dipole moment 4π Am2 is bent in the form of semicircle. The new magnetic moment is (A) 4π Am2 (B) 8π Am2 (C) 4 textA textm2  (D) 8 textA textm2

Tardigrade Admin · Accepted Answer

Here, Mi=4 π m L=4 π m=(4 π/L) The new distance between poles is L1=2 r=2 (L/2 π)=(L/π) ∴ Mf=m L1=(m L/π)=(4 π/π)=4 mathrm~A mathrm~m2

Q. A magnetic wire of dipole moment $4 π A m^{2}$ is bent in the form of semicircle. The new magnetic moment is

$4 π A m^{2}$

$8 π A m^{2}$

$4 A m^{2}$

$8 A m^{2}$

Here, $M_{i} = 4 π$
$m L = 4 π$
$m = \frac{4 π}{L}$
The new distance between poles is
$L_{1} = 2 r = 2 \frac{L}{2 π} = \frac{L}{π}$
$∴ M_{f} = m L_{1} = \frac{m L}{π} = \frac{4 π}{π} = 4 A m^{2}$

Q. A magnetic wire of dipole moment 4πAm2 is bent in the form of semicircle. The new magnetic moment is

4πAm2

8πAm2

4A m2

8A m2