An ESP, having intensity of 45000 V/m, must be installed to treat polluted saxaple of air (viscosity: 18 centipoise) at a rate of 1500 m/min. This sample contains charged particles (1 particle having 15 electrons charge, where, 1 electron charge is 210-19 coulomb), which have an average particle size of 0.8 mm. This ESP must have an efficiency above 90%. The length and width of the ESP is 10 m and 5 m, respectively. Assuming one extra collector plate and other conditions for standard air (-0.066 um), estimate the minimum number of plates required to have this efficiency.