Alternating current (AC) and direct current (DC). The main difference between AC and DC is the direction in which the electrons flow. In DC, the electrons flow steadily in one direction, whereas in AC, the electrons are constantly switching directions, flowing forward and then backward.
Alternating current is usually generated by an alternator (synchronous generator). A generator produces alternating current by driving a coil to rotate in a magnetic field through mechanical energy (such as hydroelectric energy, wind energy, or fossil fuel combustion). The voltage and frequency are determined by the design parameters of the generator.
Often referred to as “household electricity”, AC is a form of current in which the direction of the current and the polarity of the voltage vary periodically. AC is the most commonly used and preferred form of electricity for household appliances, offices, buildings, etc. It is also the most popular form of electricity in the world. The voltage provided by alternating current varies greatly from country to country. For example, the standard AC wall plug voltage in the United States is 120 V at 60 Hz. In the United Kingdom, the household plug voltage is 230 V at 50 Hz.
The voltage of alternating current changes from positive to negative at regular intervals, measured in hertz (Hz). Each Hz equals one positive and one negative cycle. For example, in North America, where the standard AC voltage is 110V @ 60 Hz, the current changes direction 120 times per second.
Applications of alternating current
Alternating current is widely used in household electrical systems to provide power for lighting, appliances and other devices.
Industry uses AC to power a variety of machines and equipment, such as electric motors, welding equipment, and heating devices.
Electric utilities transmit AC power from power plants to substations around the country via high-voltage transmission lines, then step down the voltage and deliver it to customers.
AC power is used in electrified railroads and subway systems to power trains.
While AC has many advantages, its high voltage and high current also pose safety risks. Exposure to AC power can lead to electric shock and fire, so strict safety practices need to be followed when using AC power equipment.
Principle of Direct Current
Direct current is a form of current in which the direction of the current and the polarity of the voltage are always the same. Unlike alternating current, the current in direct current maintains a constant direction in the circuit, flowing from the positive pole to the negative pole.
The magnitude and direction of DC current is constant. When electrons in DC flow from a high electron density to a low electron density, the frequency of DC is zero because the direction and magnitude are constant.
DC electricity can be generated in a number of ways. Chemical reactions generate DC electricity inside batteries, which are widely used in small electronic devices, flashlights, and mobile devices. Converting light energy directly into electrical energy to output DC electricity.
Applications of DC power
DC power is widely used in electronic devices, including cell phones, laptops, and tablets, which are usually powered by DC power.
In renewable energy systems, such as solar power systems, the electricity generated is DC.
In electric vehicles, a battery is used to store DC electricity and drive an electric motor to power the vehicle.
Difference between direct current and alternating current
The frequency of AC voltage depends on the individual country (mostly 50 and 60 Hz are used). Whereas the frequency of DC voltage is zero.
AC has a power factor of 0 to 1 while DC has a constant zero power factor.
A DC current graph has a constant line showing that the amplitude and direction are constant, whereas AC current can be a sine, square or triangle wave.
AC current can be transmitted over long distances with some loss, while DC current can be transmitted over very long distances using high voltage DC with very little loss.
An inverter converts DC to AC. And a rectifier converts AC to DC.
Final Summary
Both alternating current (AC) and direct current (DC) play important roles in our daily lives.
DC is a form of current with constant current direction and voltage polarity and is widely used in electronic devices, renewable energy systems and certain industrial applications. DC has the advantages of high stability, suitability for low-voltage equipment and easy energy storage, and can be adapted to different power needs through various conversion devices.
Alternating current (AC) is a form of current that varies periodically. It is generated through generators and has the advantages of high transmission efficiency, equipment compatibility and ease of conversion. AC is widely used in domestic and industrial power systems. AC power can be converted to DC power through rectifiers to meet the needs of different devices.