6 Differences between AC & DC: AC vs DC Motors

When we speak of either ac or dc, we refer to the types of electric power used to run our machines, appliances and lights running in either a domestic or industrial set up. We often mingle with ac and dc sources in our everyday lives but seldom do we know the difference between them or how we utilize them in our daily lives.

Here we have looked at the methods of generating the power sources, the different ways of utilizing them, where they are utilized, differences between ac and dc systems, and differences between their motors. Their differences are as wide as normal chairs and zero gravity chairs are.

Ac and Dc power get their names from their nature of flow of current as they transmit power to the devices that depend on them. The names which are abbreviations for Alternating and Direct Current respectively do not only represent current flow but also the voltage flow.

What is ac & when is it used?

AC is electric power generated by alternating current which when represented in a graph, creates a sinusoidal waveform which ranges from the negative to the positive side. When it is in positive form the graph is usually on the upper part of the wave and when in negative the curve is on the lower side of the graph.

It alternates between the negative and the positive sides 60 times a second for electricity that is consumed in North America and 50 times a second in Great Britain. The changing of sides happens so fast that it is never detected by the human eye. The completion of 50 to 60 rotations in a second is known as hertz.

When is it Used?

Ac is preferred where the power to be produced or that has been produced needs to be manipulated for more action such as transportation to consumers far away for use. For instance, when using Ac, the electricity produced can be passed through transformers to be stepped up to very high voltages for power distribution to be made possible.

Ac is usually transmitted in high voltages over long distances to reduce the amount lost through heat by minimizing the current that is in the lines since lower current reduces heat produced through resistance.

At our homes, while using AC we should consider high quality extension cords for our outdoor activities, have a reliable circuit breaker based on your amp usage and consider which amp wires to use based on your amp rating.

extension cord

What is DC ?

Dc or direct current is the most common type of electric power learnt in schools for basic electricity classes. It is electricity generated from constant current which flows in a single direction without changing its polarity.

If plotted in a graph, current or voltage against time, it gives a straight line showing no change over time.

How is it used?

Dc is mainly used in applications of highly delicate components like motherboards that require low voltage supply and or where storage of voltage is needed for usage later. Electronic devices are the main users of dc due to reliable and constant voltage supply either from batteries or directly supplied from the mains but converted by inbuilt rectifiers.

Dc is usually tapped from electricity storage points like batteries which can be used later in portable generators, mobile phones, laptops or remote-control devices. DC is utilized by devices in our homes that require much electric care just like dracaena plants.

Solar panels generate dc power which is usually converts by inverters to ac power for usage in houses and also with some people utilizing the solar energy without converting.

Alternating vs direct current

The battle of currents has been in existence since the 1880s when the pioneers of both were still alive. Thomas Edison discovered DC while Nikola Tesla discovered AC and both worked day and night to support their currents.

However, it is Thomas Edison who is recorded to have been more scheming of the two, going to the extent of electrocuting live animals to show how dangerous Alternating Current was for consumption although it was his fear of losing royalties for the patents he had already sold.

In the 1893 Chicago World Fair, Nikola Tesla underbid to get the contract for powering the event which he won and the world got the chance to experience AC. Later that year, it was also adopted by the Niagara Falls Hydroelectric \plant which was to supply Buffalo with Electricity.

While the battle might seem to have favored AC over DC, the use of Dc is on the rise currently with computers, mobile phones, solar cells, electric vehicles and others especially devices that depend on microchips being powered by DC. Direct current is preferred due to its constant stability necessary for the devices to work.

However, the war between the two is over and they now work to complement each other. For activities that require high voltage like aluminum welding or flux core welding, AC is used with some of the best extension cords that can be acquired in the market by length in feet or by thickness which are reviewed in best extension cord chart. You can use a SAE to Metric conversion chart in the event you find charts with lengths you can’t relate with.

6 differences

Direction of flow Stability Ability to modify current and voltage values
Transport Storage Effective value

air conditioners outside

Direction of flow

The main difference between these two types of current, AC and DC, is the way they transmit electricity from one point to another and the appearance of the current when plotted on a graph.

AC when transmitting electricity changes its polarity from positive to negative, with instantaneous change in current value, which if plotted on a graph looks like a sinusoidal wave while DC transmits constant current value which if plotted on a graph gives a straight line.


When looking at stability, we consider whether it fluctuates over time when transmitting electricity. Dc transmits constant current with the same polarity while ac gives current that changes with time from one point to another and changing polarity as well.

Stability is mainly considered when looking for the best type to be used in electronic devices for optimal functionality without fail because circuit boards have chips that operate on current that flows in a single direction and does not change in value overtime.

Ability to modify values

The ability to readily and cheaply modify the current or voltage you have to the one you need to use is also another major factor usually considered while looking for the type to use.

Alternating current is easily manipulated to change, either step up or step down, the current or voltage supplied to the one that is favorable for you while for DC cannot change the current supplied from one value to another. For instance, when transmitting power is usually carried in high voltage lines but once they reach near our homes, they are reduced to values that can be consumed domestically, 110 to 120v, or in industries, 208 to 240v.


For electricity to reach our homes from providers it has to be supplied from the point of production to the point consumption which is our houses.  AC is easily transmissible over long distances due to its ability to be stepped up to increase the voltage and reduce the current thus effectively relaying it over long distances with minimal energy loss.

For DC, it is harder to convey power over long distances due to its inability to be transformed to either higher or lower voltages.


Dc power is easily tapped from storage facilities like a battery which can be utilized at any moment while AC can’t be stored for use later on.

Effective value

Effective value is the constant or average amount of voltage or current that you get when supplying to a device. The effective value Dc is higher than that of AC due to the alternating nature of AC which gives less voltage or current value for similar values with that of dc remaining constant. While using AC you need to supply more current to attain a similar effective value with DC.

air conditioning units

AC Motor vs DC Motors


Ac motors change alternating current to mechanical energy through magnetic induction and are used by most of the appliances that we use which need to be plugged into electric sockets to get electrical supply to work. AC motors are by machines as large as metal lathe machines which work on metal of different sheet metal thickness.

While DC motors use direct current, AC motors just like their name states, use AC to produce mechanical power. Also, another distinct characteristic of AC motors is they don’t use brushes in their working mechanism.

Brushes, when used, drastically reduce the life expectancy of a motor with the parts that come into contact with them requiring constant replacement due to their wearing out.

Ac motor consists of two main parts that aid in its movement; rotor and stator. The rotor is the rotating part of the motor usually connected to an external shaft to transmit the revolutionary movement needed.

The stator holds copper wires wound around it which produce a magnetic field which in turn leads to production of an electromotive force which produces the turning effect needed to turn the rotor.

DC Motor

Dc motors convert electric energy from direct current to mechanical energy which enables the motor to turn. The motors work based on the principle that once a magnetic field interacts with an electric field there is production of mechanical energy.

However, for the motor to work it depends on two main components which are; stator and armature. The stator is stationary and provides the constant magnetic field needed for the movement to happen while the armature is the rotating part connected to the dc source that provides the electric energy.

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