Q 12-04-170JEE MainJEE Main 2021 (25 Jul, Shift 2)Easy
Two ions having same mass have charges in the ratio $1 : 2$. They are projected normally in a uniform magnetic field with their speeds in the ratio $2 : 3$. The ratio of the radii of their circular trajectories is,
Answer: (B) $4 : 3$
$r = \dfrac{mv}{qB}$, so with equal masses
$$\frac{r_1}{r_2} = \frac{v_1}{v_2}\cdot\frac{q_2}{q_1} = \frac{2}{3}\times\frac{2}{1} = \frac{4}{3}$$
Solution by Sreeraj P, M.Sc Physics