Q219 / 225 · JEE Main 2005 · Physics
A charged particle of mass $\mathrm{m}$ and charge $q$ travels on a circular path of radius $r$ that is perpendicular to a magnetic field $\mathrm{B}$. The time taken by the particle to complete one revolution is
- A$\frac{2 \pi \mathrm{mq}}{\mathrm{B}}$
- B$\frac{2 \pi q^2 B}{m}$
- C$\frac{2 \pi q B}{m}$
- Correct answerD$\frac{2 \pi m}{q B}$
Solution
$\mathrm{m} \omega^2 \mathrm{r}=\mathrm{Bq} \omega \mathrm{r}$
$\omega=\mathrm{Bq} / \mathrm{m}$
$\mathrm{T}=\frac{2 \pi \mathrm{m}}{\mathrm{qB}}$
Hence, the correct answer is option: 'D'.