28. If an electron is suspended midway between two horizontal electric plates that are separated by a distance of 55 cm, what velocity will it hit the positive plate with when the plates (E = 250 N/C) are turned on?(3 marks) 29. What potential difference exists when an alpha particle reaches a speed of 5.0 m/s as it hits the negative plate in a uniform electric field?(3 marks) 25. Suppose that the ion source in a mass spectrometer produces doubly ionized gold ions (Au2+), each with a mass of 3.27 10-25 kg. The ions are accelerated through a potential difference of 1.00 kV. Then, a 0.500 T magnetic field causes the particle to follow a circular path. What is the radius of the path of the particle? (3 marks