DC (Direct Current) and AC (Alternating Current) represent the two ways in which electricity flows. Current is the movement of electrons in a wire, while the difference between DC and AC lies in the direction of electron flow. Both are essential for the operation of electronic equipment, and we will consider their differences in this blog.
Alternating current (AC) provides voltages and currents that vary over time. The voltage or current will continually be reversing direction, and therefore reversing their polarities. As the source is periodically changing, the plotted graph will be particularly sinusoidal.
For both current and voltage, the waveform changes, and in this case, becomes positive first and then negative. The time period is the time from one point in one waveform cycle to the same point in the second cycle. The time period tends to be short and therefore, milliseconds and microseconds are used. Moreover, the amplitude is the maximum signal voltage, and is measured in volts. On the other hand, the peak-peak voltage is twice the peak voltage (Amplitude). The rate of change of direction is called the AC frequency and is measured in Hertz (Hz), which is the number of cycles per second. Nonetheless, AC power is sufficient to power certain devices, such as lamps and heaters, but almost all electronic circuits require constant DC power.
Alternating current can be produced by generators, or converted from DC using inverters. However, the generator consists of a magnet and a coil that rotates in the magnetic field of the magnet. When the wire rotates in a magnetic field, the change in the strength of the magnetic field passing through the wire generates a voltage that drives the electrical charge around the wire. The voltage initially produces current in one direction along the wire. Then when the coil rotates 180 degrees, the voltage will reverse, generating current in the opposite direction along the wire. Each time the cycle rotates 180 degrees, the direction of the voltage and the current will change. After every 180 degrees of rotation, the direction of the voltage changes to generate alternating current. In addition to having magnets and wires, the generator also has slip rings to ensure that the ends of the wires are always connected to the same side of the circuit. This ensures that the direction of the current will change every half a turn.
Alternating current is mainly used in power distribution and transmission. Moreover, every house in the world is powered by alternating currents. Direct current isn’t used for such a purpose due to its high cost, risk, and power loss.
Direct current provides a constant voltage and current. However, direct current is also defined as the unidirectional flow of electrons since it moves in only one direction. When plotted, we can see that the current or voltage is steady throughout the entire period. This means that we can rely on DC sources to provide constant current/voltage. However, the battery will gradually lose its charge, and the current/voltage will drop as it is used.
Direct current is generated by energy sources such solar PV, and fuel cells. Moreover, direct current can be produced by using a rectifier that converts AC to DC.
DC circuits have many applications, but they are mainly used to power electronic devices. However, it is commonly used in low voltage devices such as computers, mobile phones, transistors, integrated circuits, etc..