A potential difference of 1.2 × 10³ V is applied between a pair of horizontal metal plates in a vacuum, as shown in Fig. 3.1. [Figure 3.1] The separation of the plates is 3.6cm. The electric field between the plates is uniform. A particle of mass 5.9 × 10⁻⁶kg and charge –4.2 × 10⁻⁹C enters the field at point X with a horizontal velocity of 0.75ms⁻¹ along a line midway between the two plates. The particle is deflected by the field and hits the top plate at point Y.