A particle of mass m, charge Q and kinetic energy T enters a transverse uniform magnetic field of induction $\overrightarrow B$. After 3 seconds the kinetic energy of the particle will be :

Question

$\begin {array} {1 1} (1)\;4T & \quad (2)\;3T \\ (3)\;2T & \quad (4)\;T \end {array}$