A bar magnet having a magnetic moment of 2.0 × 105 JT -1, is placed along the direction of uniform magnetic field of magnitude B =14 × 10-5 T. The work done in rotating the magnet slowly through 60° from the direction of field is :

Question

A bar magnet having a magnetic moment of 2.0 × 105 JT -1, is placed along the direction of uniform magnetic field of magnitude B =14 × 10-5 T. The work done in rotating the magnet slowly through 60° from the direction of field is : (A) 14 J (B) 8.4 J (C) 4 J (D) 1.4 J

Tardigrade Admin · Accepted Answer

Work done = MB ( cos θ1- cos θ2) θ1=0°, θ2=60° =2 × 105 × 14 × 10-5(1-1 / 2) =14 J

Q. A bar magnet having a magnetic moment of $2.0 \times 1 0^{5} J T^{- 1}$ , is placed along the direction of uniform magnetic field of magnitude $B = 14 \times 1 0^{- 5} T$ . The work done in rotating the magnet slowly through $6 0^{\circ}$ from the direction of field is :

$14 J$

$8.4 J$

$4 J$

$1.4 J$

Work done $= MB (cos θ_{1} - cos θ_{2})$
$θ_{1} = 0^{\circ}, θ_{2} = 6 0^{\circ}$
$= 2 \times 1 0^{5} \times 14 \times 1 0^{- 5} (1 - 1/2)$
$= 14 J$

Q. A bar magnet having a magnetic moment of 2.0×105JT−1, is placed along the direction of uniform magnetic field of magnitude B=14×10−5T. The work done in rotating the magnet slowly through 60∘ from the direction of field is :

14J

8.4J

4J

1.4J