Question

The figure shows two regions of uniform magnetic fields of strengths $B$ and $2B$ . A charged particle of mass $m$ and charge $q$ enters the region of the magnetic field with a velocity $v=\frac{qBw}{m}$ , where $w$ is the width of each region of the magnetic field. The time taken by the particle to come out of the region of the magnetic field is

• A. $\frac{4\pi m}{qB}$
• B. $\frac{2\pi m}{qB}$
• C. $\frac{\pi m}{2qB}$
• D. $\frac{\pi m}{qB}$

Answer 1

Answer: (D)

$\text{Time}=\frac{\pi \text{m}}{2\text{qB}}+\frac{\pi \text{m}}{2\text{qB}}=\frac{\pi \text{m}}{qB}$