A ceiling fan having 3 blades of length $80 \mathrm{~cm}$ each is rotating with an angular velocity of 1200 $\mathrm{rpm}$. The magnetic field of earth in that region is $0.5 \mathrm{G}$ and angle of dip is $30^{\circ}$. The emf induced across the blades is $\mathrm{N} \pi \times 10^{-5} \mathrm{~V}$. The value of $\mathrm{N}$ is _________.
Answer (integer)
32
Solution
<p>$$\begin{aligned}
& B_v=B \sin 30=\frac{1}{4} \times 10^{-4} \\
& \omega=2 \pi \times f=\frac{2 \pi}{60} \times 1200 \mathrm{~rad} / \mathrm{s} \\
& \varepsilon=\frac{1}{2} B_V \omega \ell^2 \\
& =32 \pi \times 10^{-5} \mathrm{~V}
\end{aligned}$$</p>
About this question
Subject: Physics · Chapter: Electromagnetic Induction · Topic: Motional EMF
This question is part of PrepWiser's free JEE Main question bank. 66 more solved questions on Electromagnetic Induction are available — start with the harder ones if your accuracy is >70%.