In general, if a charged particle is accelerated between two metal plates/a region by a potential difference V volts, the work done on the charge, given by the product of the charge and the potential difference, is equal to the kinetic energy of the charge
Thus eV = K.E
1.6 x 10\(^{-19}\) x V = 4.8 x 10\(^{-17}\)

 ∴ V = \(\frac{4.8 \times 10^{-17}}{1.6 \times 10^{-19}}\)

= 300V