What is the difference between ac and dc voltage

The direct current does not have any specific waveform because it only flows in a single direction. If you connect a DC to an oscilloscope, it will show a straight line.

However, if the voltage is pulsating, say in a digital circuit that purely runs on DC voltages, the signal waveform might appear as a pulse train or square waves. But the waveform never falls below 0V.

DC Current. DC Voltage. DC Resistance. DC Power. We need both types of electric current in our daily life application. Digital devices such as smartphones, laptops and computers, etc. The Alternating current and direct current are interchangeable. They can be easily converted from one form to the other.

We use both of them to convert between the power supplies according to our needs. The outlets in our home provide AC supply but when we need to power a DC device using the same outlet, we use a rectifier such as the power supply in PC or the power adapter in a laptop cable. It helps us using the same power source to power both types of devices.

But there is a limitation of the alternating current i. Therefore, the AC is converted into smooth DC before charging a battery such as in cellphones. The charge storage provides mobility and wireless capability to the device. It is also used as an emergency backup in harsh conditions to power crucial equipment such as in hospitals etc.

The transmission lines experience power loss I 2 R in the form of heat due to the amount of current flowing through them. In AC, the voltages can be easily converted between high and low voltages using a device called a Transformer. We use Step-Up Transformers at the generation stations to bump up the voltages for transmission over long distances.

Also, the same voltages are brought down to safe levels for domestic or commercial uses using the Step-Down Transformer usually seen on utility poles. There is very little loss in high voltage DC transmission and it requires only two wires but its maintenance and conversion between high and low voltage is very costly so it was never adopted.

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Check Also. Close Search for. AC can be converted to and from high voltages easily using transformers. AC is also capable of powering electric motors. Motors and generators are the exact same device, but motors convert electrical energy into mechanical energy if the shaft on a motor is spun, a voltage is generated at the terminals! This is useful for many large appliances like dishwashers, refrigerators, and so on, which run on AC. Direct current is a bit easier to understand than alternating current.

Rather than oscillating back and forth, DC provides a constant voltage or current. The tank can only push water one way: out the hose. Similar to our DC-producing battery, once the tank is empty, water no longer flows through the pipes.

DC is defined as the "unidirectional" flow of current; current only flows in one direction. Voltage and current can vary over time so long as the direction of flow does not change.

To simplify things, we will assume that voltage is a constant. For example, we assume that a AA battery provides 1. What does this mean? It means that we can count on most DC sources to provide a constant voltage over time. In reality, a battery will slowly lose its charge, meaning that the voltage will drop as the battery is used. For most purposes, we can assume that the voltage is constant. Almost all electronics projects and parts for sale on SparkFun run on DC. Examples of DC electronics include:.

Almost every home and business is wired for AC. However, this was not an overnight decision. In the late s, a variety of inventions across the United States and Europe led to a full-scale battle between alternating current and direct current distribution. Thomas Edison, on the other hand, had constructed DC power stations in the United States by A turning point in the battle came when George Westinghouse, a famous industrialist from Pittsburgh, purchased Nikola Tesla's patents for AC motors and transmission the next year.

Thomas Edison Image courtesy of biography. In the late s, DC could not be easily converted to high voltages. As a result, Edison proposed a system of small, local power plants that would power individual neighborhoods or city sections. Even though the voltage drop across the power lines was accounted for, power plants needed to be located within 1 mile of the end user. This limitation made power distribution in rural areas extremely difficult, if not impossible. With Tesla's patents, Westinghouse worked to perfect the AC distribution system.

Transformers provided an inexpensive method to step up the voltage of AC to several thousand volts and back down to usable levels. At higher voltages, the same power could be transmitted at much lower current, which meant less power lost due to resistance in the wires. As a result, large power plants could be located many miles away and service a greater number of people and buildings. Over the next few years, Edison ran a campaign to highly discourage the use of AC in the United States, which included lobbying state legislatures and spreading disinformation about AC.

Edison also directed several technicians to publicly electrocute animals with AC in an attempt to show that AC was more dangerous than DC.

In attempt to display these dangers, Harold P. In , the International Electro-Technical Exhibition was held in Frankfurt, Germany and displayed the first long distance transmission of three-phase AC, which powered lights and motors at the exhibition. Several representatives from what would become General Electric were present and were subsequently impressed by the display. The following year, General Electric formed and began to invest in AC technology.

Westinghouse won a contract in to build a hydroelectric dam to harness the power of Niagara falls and transmit AC to Buffalo, NY. The project was completed on November 16, and AC power began to power industries in Buffalo. This milestone marked the decline of DC in the United States. However, due to the high cost and maintenance of the Thury systems, HVDC was never adopted for almost a century.

With the invention of semiconductor electronics in the s, economically transforming between AC and DC became possible. Specialized equipment could be used to generate high voltage DC power some reaching kV. In DC, the electrons flow steadily in a single direction, or "forward. A magnetic field near a wire causes electrons to flow in a single direction along the wire, because they are repelled by the negative side of a magnet and attracted toward the positive side.

This is how DC power from a battery was born, primarily attributed to Thomas Edison's work. AC generators gradually replaced Edison's DC battery system because AC is safer to transfer over the longer city distances and can provide more power.

Instead of applying the magnetism along the wire steadily, scientist Nikola Tesla used a rotating magnet. When the magnet was oriented in one direction, the electrons flowed towards the positive, but when the magnet's orientation was flipped, the electrons turned as well.

Another difference between AC and DC involves the amount of energy it can carry. Each battery is designed to produce only one voltage, and that voltage of DC cannot travel very far until it begins to lose energy.

But AC's voltage from a generator, in a power plant, can be bumped up or down in strength by another mechanism called a transformer. Transformers are located on the electrical pole on the street, not at the power plant.

They change very high voltage into a lower voltage appropriate for your home appliances, like lamps and refrigerators. AC can even be changed to DC by an adapter that you might use to power the battery on your laptop. DC can be "bumped" up or down, it is just a little more difficult. Inverters change DC to AC. For example, for your car an inverter would change the 12 volt DC to Volt AC to run a small device. While DC can be stored in batteries, you cannot store AC.