Question

A magnetic dipole is free to rotate in a
uniform magnetic field. For what
orientation of the with respect to the
magnetic field
a) Torque is maximum b) Potential
energy is maximum

Answer 1

Answer:

Explanation:

(a) As τ→=M−→×B→ i.e. τ=MBsinθ,

so torque will be maximum when sinθ=max.=1.

∴θ=90∘.

(b) As P.E. =−MBcosθ,

therefore, P.E. will be maximum (=MB), when

cosθ=−1, i.e., θ=180∘ as shown in figure.

(c) From τ=MBsinθ,dtaudθ=MBcosθ. Now dtaudθ will be maximum when cosθ=max.=1, i.e., θ=0∘.

i.e., M−→ is along B→