Join the Most Relevant JEE Main 2025 Test Series & get 99+ percentile! Join Now
Search any question & find its solution
Question: Answered & Verified by Expert
Charge $q$ is uniformly spread on a thin ring of radius $R$. The ring rotates about its axis with a uniform frequency $f \mathrm{~Hz}$. The magnitude of magnetic induction at the centre of the ring is
PhysicsMagnetic Effects of CurrentNEETNEET 2011 (Mains)
Options:
  • A $\frac{\mu_0 q f}{2 R}$
  • B $\frac{\mu_0 q}{2 f R}$
  • C $\frac{\mu_0 q}{2 \pi f R}$
  • D $\frac{\mu_0 q f}{2 \pi R}$
Solution:
1024 Upvotes Verified Answer
The correct answer is: $\frac{\mu_0 q f}{2 R}$
We know
$$
\begin{array}{ll}
B=\frac{\mu_0 i}{2 R} \\
q=i t \Rightarrow i=\frac{q}{t}=q f \quad\left[\because f=\frac{1}{t}\right] \\
B=\frac{\mu_0 q f}{2 R}
\end{array}
$$

Looking for more such questions to practice?

Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.