Final answer:
Welding machines use low voltage and high amperage to effectively weld metals, with low voltage ensuring safety and high amperage providing the necessary heat.
Step-by-step explanation:
The output of a welding machine is typically characterized by low voltage and high amperage. This is because the welding process requires significant current to generate the heat necessary for melting metal, but the voltage doesn't need to be high. In fact, using high voltage might be dangerous in such applications and is not needed for the welding process. Low voltage helps to minimize the risk of electric shock, while the high amperage ensures there's enough current to effectively heat and join the metals being welded.
Concerning electric power transmission, the principle that allows for either high current with low voltage or vice versa to achieve a certain power level (Power = I V) is also indicative of why welding machines operate at low voltage and high amperage. For power transmission, high voltage and low current are preferred to reduce ohmic losses, whereas for welding, high current is necessary for the process efficiency but can be delivered at low voltage for safety and practicality.