Question

Electrons at rest are accelerated by a potential of $V$ volt. These electrons enter the region of space having a uniform, perpendicular magnetic induction field $B$. The radius of the path of the electrons inside the magnetic field is:

• A. $1/B\sqrt{mV/e}$
• B. $\frac{\sqrt{2mV/e}}{B}$
• C. $mV/qB$
• D. $1/B\sqrt{V/e}$

Answer 1

The correct option is B $\frac{\sqrt{2mV/e}}{B}$

$R=\frac{mV}{qB}$

$R=\frac{P}{qB}=\frac{\sqrt{2meV}}{eB}$

$R=\frac{\sqrt{2m\frac{V}{e}}}{B}$