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(a) Derive the expression for the torque acting on a current-carrying loop placed in a magnetic field.
(b) Explain the significance of a radial magnetic field when a current-carrying coil is kept in it.

Answers (1)

Let us consider a loop ABCD in a uniform magnetic field of strength B. and Let the current through the loop be I.

Consider force F_{1} on arm AB and force F_{2} on arm CD.

F_{1}=F_{2}=IbB

The net torque is given by -

\tau = I\: \frac{a}{2}\: b\: B\: +I\: \frac{a}{2}\: b\: B\:

\tau = IAB

Where A is the area of the loop

Now,

The magnetic moment of the loop.

\vec{m}=I\vec{A}

Therefore

\tau = mB

This is the expression for the torque acting on a current-carrying loop placed in a magnetic field.

(b) In a radial magnetic field, two sides of the rectangular coil remain perpendicular and other two ides remain parallel to magnetic field lines in all position of the coil.

Posted by

Safeer PP

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