Question

The armature of a demonstrator generator consists of a flat square coil of side $4cm$ and $200$ turns. The coil rotates in a magnetic field of $0.75T$. The angular speed so that a maximum emf of $1.6V$ is generated is:

• A. $\frac{20}{3}$ rad/s
• B. $\frac{10}{3}$ rotations/s
• C. $\frac{40}{3}$ rpm
• D. None of these

Answer 1

The correct option is A $\frac{20}{3}$ rad/s

Maximum emf of a rotating coil ${\epsilon }_{max}=N{A}_{0}B\omega$ or
$\omega =\frac{{\epsilon }_{max}}{N{A}_{0}B}$
$=\frac{1.6}{200\times 16\times {10}^{-4}\left(.75\right)}$
$=\frac{20}{3}rad/s$