Q98 / 180 · AIIMS 2011 · Physics
Mutual inductance $M$ between two concentric coils of radii $1 \mathrm{~m}$ and $2 \mathrm{~m}$ is
- A$\frac{\mu_0 \pi}{2}$
- Correct answerB$\frac{\mu_0 \pi}{4}$
- C$\frac{\mu_0 \pi}{8}$
- D$\frac{\mu_0 \pi}{10}$
Solution
Here, $r_1=1 \mathrm{~m}, r_2=2 \mathrm{~m}$
$$
\text { Mutual inductance, } \begin{aligned}
M & =\frac{\mu_0 \pi r_1^2}{2 r_2} \\
& =\frac{\mu_0 \pi \times 1}{2 \times 2}=\frac{\mu_0 \pi}{4}
\end{aligned}
$$
Hence, the correct answer is option: 'B'.