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 -
JEE MAIN 2021, Medium
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$R =\frac{ mv }{ qB }$
$\Rightarrow \frac{ R _{1}}{ R _{2}}=\frac{\frac{ mv _{1}}{ q _{1} B }}{\frac{ mv _{2}}{ q _{2} B }}=\frac{ v _{1}}{ q _{1}} \times \frac{ q _{2}}{ v _{2}}=\frac{ q _{2}}{ q _{1}} \times \frac{ v _{1}}{ v _{2}}$
$=\frac{2}{ l } \times\left(\frac{2}{3}\right)=\frac{4}{3}$
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