Answer: The primary difference between AC (Alternating Current) and DC (Direct Current) transmission lies in the nature of the current flow and their application.

• AC Transmission: This is the most common method for power grids. The current periodically reverses direction, which makes it easy to change voltage levels using transformers. AC systems are generally less expensive to build and are well-suited for shorter and medium distances.

• DC Transmission: In this method, current flows in a single direction. While it requires more complex equipment to convert between AC and DC at each end of the line, it is significantly more efficient for very long distances and for transmitting power via underwater cables. HVDC (High-Voltage Direct Current) systems have lower power losses over long distances and can be used to connect different AC grids that are not synchronized.