Q149 / 160 · TS EAMCET 2018 (04 May Shift 2) · Physics
A moving coil galvanometer has a rectangular wire coil of enclosed area $0.001 \mathrm{~m}^2$ and 500 turns. The coil operates in a radial magnetic field of $0.2 \mathrm{~T}$ and carries a current of $6 \pi \times 10^{-8} \mathrm{~A}$. If the torsional spring constant is $6 \times 10^{-7} \mathrm{~N}-\mathrm{m} / \mathrm{rad}$, then the angular deflection of the coil in radians is
- Correct answerA$\frac{\pi}{100}$
- B$\frac{\pi}{200}$
- C$\frac{\pi}{300}$
- D$\frac{\pi}{400}$
Solution
Angular deflection of a moving coil galvanometer is given by
$$
\begin{aligned}
\theta & =\left(\frac{N B A}{k}\right) i \\
& =\frac{500 \times 0.2 \times 0.001}{6 \times 10^{-7}} \times 6 \pi \times 10^{-8} \\
& =\frac{5 \times 0.2 \times 10^{-1} \times 6 \pi \times 10^{-8}}{6 \times 10^{-7}} \\
\theta & =\frac{\pi}{100}
\end{aligned}
$$
Hence, the correct answer is option: 'A'.