Which type of current flow is determined by the polarity of the circuit?

Direct current (DC) is characterized by the flow of electric charge in a single direction, and its polarity remains constant over time. In a DC circuit, one terminal is always positive and the other is negative, which influences how the current flows within the circuit. This unidirectional flow allows for consistent voltage levels and polarity, making DC suitable for a variety of applications such as batteries, electronic devices, and power converters.

In contrast, alternating current (AC) periodically reverses its direction and changes its polarity. This characteristic of AC means that it does not maintain a consistent polarity, making it distinct from DC. High frequency and low frequency currents, while potentially being either AC or DC depending on their specific characteristics, further complicate the context since their classification does not inherently relate to the determination of polarity in a static manner as seen with direct current.