Question

An ion has a positive charge numerically equal to twice the electronic charge. The mass of the ion is 7000 times that of an electron. The ion is initially stationary and accelerated through a potential difference of 200 V. Calculate the velocity acquired by the ion.

Answer 1

$$\dfrac{1}{2}mv^2=qV,$$ $$v=\sqrt{\dfrac{2qV}{m}},$$ $$v=\sqrt{\dfrac{2\cdot2\cdot1.6\cdot10^{-19}\ C\cdot200\ V}{7000\cdot9.11\cdot10^{-31}\ kg}}=1.42\cdot10^5\ \dfrac{m}{s}.$$