Image description

The image shows in parallel two flow types of electric charges, respectively of the movement of electrons in a circuit, these being represented by the alternating current, the first image, and by the direct current, the second image.

The alternating and direct current are illustrated in a diagram with two axes, one vertical, left, of voltage, and another horizontal, down, of time.

The first image shows the flow of electric current, alternating its direction, with oscillations in the form of up and down loops, or in the form of pulses, whose voltage may vary depending on the transformer that transforms this voltage, increasing or decreasing it, so as to be adapted to the needs of the final consumer.

A good example of the use of alternating current is the electricity distribution network through cables and high voltage lines, which are changed to medium or low voltage through the transformer substation before reaching the consumer.

The alternating current is rendered by a wavy, horizontal, thickened line, above another straight line, parallel to it, but thinner, representing the determined time axis.

In the second image is illustrated the one-way direction of the electricity flow, the motion of electrons or ions, thus being called direct current, electric current flowing in a constant direction, distinguishing it from alternating current.

A typical example of direct current use is in a battery.

The direct current is rendered by a horizontal, straight, thickened line, above another line parallel to it, but thinner, representing the determined time axis.

General information

Just as the air flowing from one point to another creates an air current, the flow of electrons is called an electric current

The direct current (abbreviated as DC) is an electric current that does not change its flow, meaning the transfer of electrons always takes place from the negative end towards the positive end of the source of current. One example of a source for direct current are the batteries. Examples of electric devices using direct current are watches, mobile phones and toy cars powered by a small engine or motor.

The alternating current (abbreviated as AC) is an electric current that changes its flow on a regular basis, at a certain time interval. The biggest advantage of the alternating current is the fact that it can be transmitted over long distances with minimal loss. In addition, it is the current that can be converted with the help of transformer stations which increase or decrease the voltage, in order to suit the consumers’ needs. The most commonly seen sources of alternating current are the sockets from our houses. Here the current can change its flow fifty times per second.

Did you know that many plug-in appliances use direct current even if they are charged by using a socket, which actually uses alternating current? For example, a mobile phone is charged with alternating current, but the battery is charged using direct current. The charger contains a circuit that decreases the voltage from two hundred twenty volts to five volts, then it converts the alternating current into direct current.


  1. https://www.setthings.com/ro/curent-continuu-si-curent-alternativ/
  2. https://ro.wikipedia.org/wiki/Curent_continuu
  3. https://www.baluna.ro/diferenta-intre-curent-continuu-si-curent-alternativ/

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