The circuit through which DC current passes is called DC circuit, which is a closed conductive loop composed of DC power supply and resistor. In this DC circuit, a constant electric field is formed. Outside the power supply, positive charge flows from high potential to low potential through resistance. In the power supply, the electrostatic force is overcome by the non-electrostatic force of the power supply, and then it reaches the high potential from the low potential, and so on, forming a closed current line.
The magnitude and direction of alternating current alternate with periodically changing current at any time, and the average running value in a period is zero. Unlike direct current, its direction changes with time, while direct current does not change periodically.
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The difference between alternating current and direct current
Alternating current: The magnitude and direction change periodically. In life, plug-in appliances use civil AC power.
Direct current: the direction does not change with time. The mobile external power supply used in life provides direct current.
Alternating current is widely used in family life and industrial production. The household voltage is 220V, and the general industrial voltage is 380V, which are all dangerous voltages.
Direct current is widely used in small household appliances such as flashlights (dry batteries) and mobile phones (lithium batteries). Dry battery (1.5V), lithium battery and storage battery are called DC power supply. Because the voltage of these power supplies will not exceed 24V, they are safe power supplies.
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