Magnetic Effects Of Current Question 18
Question 18 - 31 January - Shift 1
A bar magnet with a magnetic moment $5.0 Am^{2}$ is placed in parallel position relative to a magnetic field of $0.4 T$. The amount of required work done in turning the magnet form parallel to antiparallel position relative to the field direction is
(1) $4 J$
(2) $1 J$
(3) $2 J$
(4) Zero
Show Answer
Answer: (1)
Solution:
Formula: Potential Energy Of A Magnetic Dipole
$u=-MB \cos \theta$
$W=\Delta u$
$W=-MB \cos 180^{\circ}(-mB \cos 0^{\circ})$
$W=2 MB=2 \times 5 \times 0.4=4 J$
Option 1
