Question

An electron is accelerated in a vacuum from rest through a potential difference of 850V.

Show that the final momentum of the electron is 1.6 × 10–23 N s.

Answer 1

The motion of an electron with that energy is nonrelativistic, so you can feel free to use
\[ p = \sqrt{2mE } \]
where
\[ E = e\cdot \Delta V \]
\[ e = 1.6\cdot 10^{-19} \text{ C} \]
\[\Delta V = 850 \text{ V }\]
\[ m = 9.1 \cdot 10^{-31} \text{ kg} \]