Question

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

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

Answer 1

Answer: (A)

$\sqrt {\frac {2eV}{m}}$

Answer 2

The kinetic energy of an electron
$\frac {1}{2}\times mv^2=eV$
or final velocity of electron (v) $= \sqrt {\frac {2eV}{m}}.$