A bar magnet has a magnetic moment 2.5 J T -1 and is placed in a magnetic field of 0.2 T. The work done in turning the magnet from parallel to antiparallel position relative to field direction is

Question

A bar magnet has a magnetic moment 2.5 J T -1 and is placed in a magnetic field of 0.2 T. The work done in turning the magnet from parallel to antiparallel position relative to field direction is (A) 1 J (B) 2 J (C) 3 J (D) 4 J

Tardigrade Admin · Accepted Answer

Work done in changing the orientation of a dipole of moment

M

in a magnetic field

B

from position

θ_{1}

to

θ_{2}

is given by

W = MB (cos θ_{1} - cos θ_{2})

Here,

θ_{1} = 0^{\circ}

and

θ_{2} = 18 0^{\circ}

So,

W = 2 MB = 2 \times 2.5 \times 0.2 = 1 J

Q. A bar magnet has a magnetic moment 2.5JT−1 and is placed in a magnetic field of 0.2T. The work done in turning the magnet from parallel to antiparallel position relative to field direction is

1 J

2 J

3 J

4 J

Work done in changing the orientation of a dipole of moment M in a magnetic field B from position θ1​ to θ2​ is given by W=MB(cosθ1​−cosθ2​) Here, θ1​=0∘ and θ2​=180∘ So, W=2MB=2×2.5×0.2=1J

Q. A bar magnet has a magnetic moment $2.5 J T^{- 1}$ and is placed in a magnetic field of $0.2 T$ . The work done in turning the magnet from parallel to antiparallel position relative to field direction is

Work done in changing the orientation of a dipole of moment $M$ in a magnetic field $B$ from position $θ_{1}$ to $θ_{2}$ is given by
$W = MB (cos θ_{1} - cos θ_{2})$
Here, $θ_{1} = 0^{\circ}$ and $θ_{2} = 18 0^{\circ}$
So, $W = 2 MB = 2 \times 2.5 \times 0.2 = 1 J$