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What is the difference between alternating current and direct current?

Definition:

• Alternating current (AC):The direction of the current changes periodically, that is, the current will flow in the forward and reverse directions within one cycle.Alternating current is used in power grids in most countries to provide power for households and industries.

• Direct current (DC):The direction of the current is always constant, that is, the current only flows in one direction.Direct current is mainly used in battery-powered devices, electronic equipment, and some specific industrial applications

  
  

Waveform:

• Alternating current:The waveform is usually a sinusoidal wave (Sinusoidal Wave), but it can also be in other forms such as square waves and triangular waves.The sinusoidal waveform is the most common alternating current waveform in the power grid and has good electromagnetic compatibility and energy transmission characteristics.

• Direct current:The waveform is a straight line indicating that the current is constant.Direct current sometimes has fluctuations (such as pulsating direct current), but in most cases, direct current is considered stable.

  
  

Transmission and loss:

• Alternating current:Due to the frequency effect of alternating current, the current flows on the surface of the wire (skin effect), which leads to higher losses when the transmission distance is longer.Alternating current can be easily stepped up or down by transformers for long-distance transmission.

• Direct current:When direct current is transmitted over a long distance, there is theoretically lower loss because there is no skin effect.
  Direct current cannot be directly transformed by traditional transformers. Electronic devices such as inverters and rectifiers are needed for voltage conversion.