A bar magnet of magnetic moment $2 {Am}^{2}$ is free to rotate about a vertical axis passing through its centre. The magnet is then released from rest at east -west position. Find the Kinetic energy of the magnet as it takes north-south position is ________ $μ J$ $(B_{H} = 25 μ T)$ (Give integer value)

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Solution

Kinetic energy of barmagnet in the presence of external magnetic field is , $K = M B_{H} [1 - cos θ]$

From the data given in the question, $θ = 90^{\circ} \Rightarrow cos 90^{\circ} = 0$

$∴ K = M B_{H}$

Substituting the given data we get,

$K = 2 \times 25 \times 10^{- 6}$
$= 50 \times 10^{- 6} J$
$= 50 μ J$

Accepted answer : $50$

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A bar magnet of magnetic moment 2 Am2 is free to rotate about a vertical axis passing through its centre. The magnet is then released from rest at east -west position. Find the Kinetic energy of the magnet as it takes north-south position is ________μJ (BH=25μT) (Give integer value)

Kinetic energy of barmagnet in the presence of external magnetic field is , K=MBH[1−cosθ] From the data given in the question, θ=90∘⇒cos90∘=0 ∴K=MBH Substituting the given data we get, K=2×25×10−6 =50×10−6 J =50 μJ Accepted answer : 50