A circular coil having 200 turns, $2.5 \times 10^{-4} \mathrm{~m}^2$ area and carrying $100 \mu \mathrm{A}$ current is placed in a uniform magnetic field of $1 \mathrm{~T}$. Initially the magnetic dipole moment $(\vec{M})$ was directed along $\vec{B}$. Amount of work, required to rotate the coil through $90^{\circ}$ from its initial orientation such that $\vec{M}$ becomes perpendicular to $\vec{B}$, is ________ $\mu$J.
Answer (integer)
5
Solution
<p>$$\begin{aligned}
& W=U_f-U_i=(-M B \cos 90)-(-M B \cos 0) \\
& \Rightarrow W=M B=N i A B=5 \mu \mathrm{J}
\end{aligned}$$</p>
About this question
Subject: Physics · Chapter: Magnetic Effects of Current · Topic: Biot-Savart Law
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