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
A point charge $Q=\left(=3 \times 10^{-12} \mathrm{C}\right)$ rotates uniformly in a vertical circle of radius $\mathrm{R}=1 \mathrm{~mm}$. The axis of the circle is aligned along the magnetic axis of the earth. At what value of the angular speed $\omega$, the effective magnetic field at the center of the circle will be reduced to zero? (Horizontal component of Earth's magnetic field is 30 micro Tesla)
PhysicsElectrostaticsKVPYKVPY 2015 (SB/SX)
Options:
  • A $\mathrm{10}^{11} \mathrm{rad} / \mathrm{s}$
  • B $10^{9} \mathrm{rad} / \mathrm{s}$
  • C $10^{13} \mathrm{rad} / \mathrm{s}$
  • D $10^{7} \mathrm{rad} / \mathrm{s}$
Solution:
1319 Upvotes Verified Answer
The correct answer is: $\mathrm{10}^{11} \mathrm{rad} / \mathrm{s}$
$$
\frac{\mu_{0}}{2 R} \cdot\left(\frac{\omega \cdot q}{2 \pi}\right)=30 \times 10^{-6}
$$
So $\omega=10^{11} \mathrm{rad} / \mathrm{s}$

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.