Question

An electron of mass $m$ and charge $e$ accelerated from rest through a potential difference $V$ in vacuum. Its final speed will be:

• A. $\sqrt{\frac{2eV}{m}}$
• B. $\sqrt{\frac{eV}{m}}$
• C. $\sqrt{\frac{eV}{2m}}$
• D. $\frac{eV}{m}$

Answer 1

The correct option is A $\sqrt{\frac{2eV}{m}}$

Let final speed is $v$.

$\Rightarrow \frac{1}{2}m{v}^2=eV$ $\Rightarrow v=\sqrt{\frac{2eV}{m}}$