A rectangular coil with 200 turns has length and width

PHYSICS · Subjective · CBSE · Physics · Moving Charges and Magnetism · Moving Charges and Magnetism

Problem

A rectangular coil with 200 turns has length

4.0\,\text{cm}

and width

3.0\,\text{cm}

. The coil is suspended between the pole pieces of a magnet producing a uniform magnetic field of

0.25\,\text{T}

. The suspension system behaves like a torsion spring of torsional constant

k=2.0\times10^{-5}\,\text{N m rad}^{-1}

. (i) Calculate the current that must be passed through the coil so that it comes to rest at a deflection of

0.20\,\text{rad}

. (ii) If, keeping all other parameters unchanged, the coil is replaced by another coil whose length and width are each doubled, determine the current required for the same angular deflection of

0.20\,\text{rad}

Related theory

Current Loops & Dipoles
Torque on current loop
Torque on a current loop
Moving Charges and Magnetism

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