Semiconductor Devices And Logic Gates

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 $=9 \times 10^{-31} \mathrm{~kg}$ )