A magnet of magnetic moment M is situated with its axis along the direction of a magnetic field of strength B. The work done in rotating it by an angle of 180° will be

Question

A magnet of magnetic moment M is situated with its axis along the direction of a magnetic field of strength B. The work done in rotating it by an angle of 180° will be (A) -M B (B) +M B (C) 0 (D) +2 M B

Tardigrade Admin · Accepted Answer

Work done =M B( cos θ1- cos θ2) θ1=0° and θ2=180° ⇒ W =M B( cos 0°- cos 180°)=2 M B

Q. A magnet of magnetic moment $M$ is situated with its axis along the direction of a magnetic field of strength $B$ . The work done in rotating it by an angle of $18 0^{\circ}$ will be

-M B

+M B

0

+2 M B

Work done $= MB (cos θ_{1} - cos θ_{2})$
$θ_{1} = 0^{\circ}$ and $θ_{2} = 18 0^{\circ}$
$\Rightarrow W = MB (cos 0^{\circ} - cos 18 0^{\circ}) = 2 MB$

Q. A magnet of magnetic moment M is situated with its axis along the direction of a magnetic field of strength B. The work done in rotating it by an angle of 180∘ will be

-M B

+M B

0

+2 M B

Work done =MB(cosθ1​−cosθ2​) θ1​=0∘ and θ2​=180∘ ⇒W=MB(cos0∘−cos180∘)=2MB

Q. A magnet of magnetic moment $M$ is situated with its axis along the direction of a magnetic field of strength $B$ . The work done in rotating it by an angle of $18 0^{\circ}$ will be

Work done $= MB (cos θ_{1} - cos θ_{2})$
$θ_{1} = 0^{\circ}$ and $θ_{2} = 18 0^{\circ}$
$\Rightarrow W = MB (cos 0^{\circ} - cos 18 0^{\circ}) = 2 MB$