A positively charged particle, having charge q, is accelerated by a potential difference V. This particle, moving along the x-axis, enters a region where a constant electric field E exists. The direction of electric field is along positive y-axis. The electric field E exists in the region bounded by the lines x = 0 and x = a. Beyond the line x = a (i.e., in region x ≥ a), there exists a constant magnetic field of strength B, directed along positive y-axis. What is the pitch of helix formed after particle enters the region x ≥ a? (mass of the particle is m).