Question

The charge and mass of a particle are $2$ times and $4000$ times the charge and mass of an electron respectively, and is at rest. If this particle is accelerated through a potential difference of $5\text{V}$ then its final kinetic energy will be-

• A. $5\text{eV}$
• B. $10\text{eV}$
• C. $15\text{eV}$
• D. $20\text{eV}$

Answer 1

The correct option is B $10\text{eV}$

From, work-energy theorem,

Work done $=$ change in $K.E$

$qV=K{E}_f-K{E}_i[\because K{E}_i=0]$

$\Rightarrow K{E}_f=V\left(2e\right)$

$K{E}_f=5\times 2\times 1.6\times {10}^{-19}J\text{(or)}$

$K{E}_f=10\text{eV}$

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Hence, $\left(B\right)$ is the correct answer.