Q 12-02-159JEE MainJEE Main 2020 (3 Sep, Shift 2)Easy
Hydrogen ion and singly ionized helium atom are accelerated, from rest, through the same potential difference. The ratio of final speeds of hydrogen and helium ions is close to:
Answer: (C) $2 : 1$
$qV = \tfrac12mv^{2} \Rightarrow v = \sqrt{\dfrac{2qV}{m}}$. Both ions carry charge $e$; their masses are in the ratio $1 : 4$.
$$\frac{v_H}{v_{He}} = \sqrt{\frac{4}{1}} = 2$$
Solution by Sreeraj P, M.Sc Physics