\(\Rightarrow \frac{ R _{1}}{ R _{2}}=\frac{\frac{ mv _{1}}{ q _{1} B }}{\frac{ mv _{2}}{ q _{2} B }}=\frac{ v _{1}}{ q _{1}} \times \frac{ q _{2}}{ v _{2}}=\frac{ q _{2}}{ q _{1}} \times \frac{ v _{1}}{ v _{2}}\)

\(=\frac{2}{ l } \times\left(\frac{2}{3}\right)=\frac{4}{3}\)