Question

An electron is accelerated through a potential difference of $500volt$. The velocity acquired by the electron is:

• A. $\frac{2}{3}\times {10}^{7}m{s}^{-1}$
• B. $\frac{1}{6}\times {10}^{7}m{s}^{-1}$
• C. $\frac{4}{3}\times {10}^{7}m{s}^{-1}$
• D. none of these

Answer 1

Answer: (C)

$\frac{4}{3}\times {10}^{7}m{s}^{-1}$

Kinetic energy acquired by electron after passing through potential difference of $500volt$:

$\frac{1}{2}{m}_e{v}^2$= $q_e$V

or, $\frac{1}{2}{v}^2=\frac{q_e}{m_e}V$

or, $v^2=\frac{q_e}{m_e}\times 2\times V$

or, $v^2=1.76\times {10}^{11}\times 2\times 500$

or, $v\approx 1.33\times {10}^{7}m{s}^{-1}=\frac{4}{3}\times {10}^{7}m{s}^{-1}$