Question 361: Electromagnetic Induction

Question

A disc of $$10.0 \mathrm{~cm}$$ diameter is rotated at speed of $$3600 \mathrm{~rpm}$$ inside a long solenoid of 1200 turns per metre on the axis of the solenoid and perpendicular to the plane of the disc. When a current of $$1.5 \mathrm{~A}$$ is passed through the solenoid, the difference in the potential between axes and circumference of the disc is nearly

Accepted Answer

Radius of the disc,
$$r=\frac{10}{2}=5 \mathrm{~cm}=0.05 \mathrm{~m}$$
Number of rotations/s $$=\frac{3600}{60}=60$$
Number of turns per unit length of solenoid,
$$\begin{aligned}
& n=1200 ~	ext {turns} / \mathrm{m} \
	herefore \quad & B=\mu_0 n l=4 \pi 	imes 10^{-7} 	imes 1200 	imes 1.5 \mathrm{~T}
\end{aligned}$$
The induced emf,
$$E=\frac{1}{2} B \omega r^2=1.08 	imes 10^{-3} \mathrm{~V}=1.08 \mathrm{~mV}$$

Answer

0.108 mV

Answer

1.08 mV

Answer

0.108 $$\mu$$V

Answer

1.08 $$\mu$$V

Electromagnetic Induction

Choose the correct answer: