Two particles X and Y having equal charges, after being accelerated through the same potential difference, enter a region of uniform mag. field and describe circular path of radius $R_1$ and $R_2$ respectively. The ratio of mass of X to that of Y is .......................
$ r = \sqrt { 2mk \over qB } $ $ r \alpha \sqrt m \Rightarrow { m_1 \over m_2 } = \left( { R_1 \over R_2 } \right) ^2 $