An electron in n-region of a p-n junction moves towards the junction with a speed of $5 \times 10^5 \mathrm{~ms}^{-1}$. If the barrier potential of the junction is 0.45 V, then the speed with which the electron enters the p-region after penetration through the barrier is (Charge of the electron $=1.6 \times 10^{-19} \mathrm{C}$ and mass of the electron $=9 \times 10^{-31} \mathrm{~kg}$ )

• Correct answer
  A

  $3 \times 10^5 \mathrm{~ms}^{-1}$
• B

  $5 \times 10^5 \mathrm{~ms}^{-1}$
• C

  $4 \times 10^5 \mathrm{~ms}^{-1}$
• D

  $6 \times 10^5 \mathrm{~ms}^{-1}$

Hence, the correct answer is option: 'A'.