X- rays are created in a standard x-ray tube by accelerating electron across a potential difference of V and having the electrons collide with a metal target to eject x-ray. when the wavelength of the x-ray is measured using Bragg diffraction from a crystal with lattice spacing 0.400nm, the first diffraction peak is at 15.0 degree. (a) what is the potential difference the electrons were accelerated across to produce the x-ray?