When voltage is applied between two electrodes, air molecules or atoms present between electrode tips get polarized, which causes positive and negative charges of an atom to get separated, creating positive and negative poles within the atom. If the voltage is increased further, these poles are not confined within the atomic boundary but get detached from each other. After detachment, they are not poles but charges—this conversion of non-charged entities into charges is ionization. The air between tips consists of charges that are collectively called plasma. The charges move toward the electrodes, which give rise to an arc that is a continuous line of charges between the electrodes. The movement faces obstacles due to the presence of other particles in the air. While overcoming the obstacles, friction occurs between moving charges and particles, which gives rise to heat. Thus, the creation of an arc can entail the creation of a heat source. Higher voltage means more ionization, stronger attraction, and a more intense arc, giving more heat. Higher current means more injection of electrons in the plasma, resulting in more ionization and a stronger arc.