What Is the Difference Between AC and DC?

Electric current refers to the movement of electrons along the conductor like a wire. Electrical energy flows in two ways, alternating current (AC) and direct current (DC). The difference between AC and DC has to do with the direction the electrons are flowing.

In direct current, electrons flow steadily in one direction (forward). In alternating current, electrons constantly change direction, sometimes going forward and sometimes backward. This periodic change of direction determines the frequency of the alternating current.

Both AC and DC describe the type of current in a circuit. Household electricity produced in power plants, flowing in power lines, and coming from a wall outlet is alternating current. A cell phone, flashlight, laptop, or other battery-powered device uses direct current.

Alternating current is best for transmitting electricity over long distances. It is widely used to carry electricity longer distances and provide more power.

On the other hand, it is more efficient to transmit electrical energy as DC rather than AC. Two converter stations are needed for this. First, it is necessary to convert AC power to DC to start the transmission process. Then it is necessary to convert the DC back to AC to connect it to the grid. This means hardware complexity and high cost.

The current graph of DC has a straight line where the magnitude and direction are constant. The graph of AC can be sinusoidal wave, square wave or triangular wave.

The rate at which the waveform repeats itself is called the frequency. The frequency of alternating current is 50 Hz or 60 Hz, depending on the country. The frequency of direct current is zero. More than 100 countries such as Germany, Italy, Spain, Turkey, Russia and China use 50 Hz frequency, while 60 Hz frequency is applied in about 40 countries including USA, Brazil, Canada, Mexico and Taiwan.

Alternating current is taken from the mains or generator. Direct current is provided by a photovoltaic cell or battery. It is possible to use alternating current by converting it to direct current and direct current to alternating current. A simple adapter can convert AC to DC. The converter that converts DC to AC is called an inverter.

Alternating current also has two different types, single-phase and three-phase. A three-phase AC is used specifically for high-voltage power transmission. Three-phase AC is converted to single-phase when sent to a household outlet.

Although the vast majority of electrical and electronic equipment prefer DC power because of its smooth flow, AC still dominates the electricity market due to the grid infrastructure. Both types of power are necessary and neither is better than the other.