A charged particle of mass 'm' and charge 'q' moving under the influence of uniform electric field $E\overrightarrow i $ and a uniform magnetic field $B\overrightarrow k $ follows a trajectory from point P to Q as shown in figure. The velocities at P and Q are respectively, $v\overrightarrow i $ and $ - 2v\overrightarrow j $ . Then which of the following statements (A, B, C, D) are the correct ?
(Trajectory shown is schematic and not to scale) :
(A) E = ${3 \over 4}\left( {{{m{v^2}} \over {qa}}} \right)$

(B) Rate of work done by the electric field at P is ${3 \over 4}\left( {{{m{v^3}} \over a}} \right)$

(C) Rate of work done by both the fields at Q is zero

(D) The difference between the magnitude of angular momentum of the particle at P and Q is 2mav.