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Difference Between AC And DC

Last updated date: 17th Apr 2024
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Comparison Between AC And DC Motor

Electric Current flows either in one Direction or keeps changing its Directions periodically. Hence, there are two ways of Current flow, namely; Alternating Current (AC) and Direct Current (DC). The major difference between AC and DC is that Current electricity flows gradually in one Direction in the Direct Current (DC). However, Current continuously varies its Direction from forward to backward and vice versa. Learn more about the points that distinguish between AC and DC. 

What is an AC Current?

The term AC refers to Alternating Current in Physics, which is highly preferred electric power for office, household equipment, and more. The critical difference between Alternating Current and Direct Current lies in the Direction in which electric charges flow. In AC, electrons continuously change their Directions from forward to backward periodically.

The curve of an Alternating Current when drawn on a graph represents the sine waveform. The curved lines denote electric cycles that are measured per second. As compared to DC Current, it’s easy to generate and transport AC across large distances. Hence, Alternating Current is widely used in buildings, powerhouses, and more. 

What is a DC Current?

DC refers to Direct Current in which there is no change in the Direction of Current flow. Hence, the major difference between AC and DC Current is the electric current flows only in One Direction in a stable voltage in DC Current. One of the major uses of DC is to charge batteries and supply power for electrical devices. In the DC circuit, electrons emerge from the negative side and move towards the positive side. The basic source of DC is produced by photovoltaic cells, batteries, or electrochemical cells.  

The above image shows that Direct Current flows in one direction. The graph shows the proportionality between the magnitude of DC and time.

Anything that uses an AC adapter while plugging into a wall or that runs on a battery depends on Direct Current. Some of the examples of DC include flashlights, mobile phone batteries, electric vehicles, and more. By going through the difference between AC Current and DC Current, it’s easy to understand why AC is most referred to across several applications. 

How Alternating Current is Converted into Direct Current?

There are several cases when there is a necessity to convert AC into DC. It’s because of the AC and DC difference that Direct Current is less preferred over long distances. To convert AC into DC, a power supply that consists of a transformer is required. Later it gets converted into Direct Current with the help of a rectifier. The conversion of AC into DC is beneficial to prevent the flow of Current from reversing. A filter used eradicated the Current pulsations in the rectifier output.

To sum up, the points of difference between AC and DC include:

Differentiate Between AC and DC Current 

Points of Difference

Alternating Current (AC)

Direct Current (DC)

Travelling Distance

It’s safe to transfer Alternating Current over long distances and maintain electric power. It can transfer between two cities. 

From comparing AC and DC Current, it’s found that DC cannot travel for far distances. It’s because DC loses electric power.

Electron Flow

In AC, electrons keep switching their Direction from frontward to backward.

Electrons only move in a forward Direction in a DC Motor.


The frequency of the Alternating Current is generally between 50 to 60 Hz. Moreover, it’s frequency depends upon the country.

The Direct Current has no or zero frequency. 

Source of Availability

The source of availability for AC Current is AC generators.

The source of availability for DC Current is either battery, electrochemical cell, or photovoltaic cell.


Generally, AC Current is of sinusoidal type. Its other types can be triangular and square trapezoidal.

The DC Current is of pure and pulsating form. 

Flowing Direction

There is a change in the Direction of the Current electricity flow due to the rotating magnets.

The Direct Current flows in a single direction due to steady magnetism. 


From the AC Current and DC Current difference, it can be said that AC is capable of powering electric Motors used on washing machines, refrigerators, and so on.

The Direct Current is preferably used in cellphones—flat-screen TVs, and so on.

Loss of Energy

As compared to DC, the loss of energy during the transmission in AC voltage is low.

DC involves a high loss of energy and is hence not preferred when transformers are at a distance. 

Ohm’s Law

Ohm’s Law frames that the voltage across an electric conductor is Directly proportional to the Current flowing via it (provided all physical necessities and temperature remain constant). Ohm’s Law is useful only when the given temperature and the other physical factors stay constant. In certain components, expanding the Current raises the temperature. For Example-  the filament of a light bulb, in which the temperature increases as the Current is increased. Ohm’s Law cannot be applied to such conditions because the Current is a variable here. The lightbulb filament breaks Ohm’s Law.

Faraday's Law

Faraday’s Law or the Law of electromagnetic induction is the essential Law of electromagnetism, which allows to indicate how a magnetic field would interact with an electric circuit to generate an emf (electromotive force) which is also called electromagnetic induction.

Faraday’s Laws of Electromagnetic Induction consists of 2 Laws. They are-

  1. Faraday’s First Law of Electromagnetic Induction- Faraday’s First Law of Electromagnetic Induction states that an emf (electromotive force) is caused in the coil when the magnetic flux across the coil varies with time.

  2. Faraday’s Second Law of Electromagnetic Induction- Faraday’s Second Law of electromagnetic induction remarks that the induced emf (electromotive force) in a coil is equivalent to the rate of change of the flux linkage.

FAQs on Difference Between AC And DC

1. What do you mean by the Universal Motor?

A universal motor can run on both DC and AC supply. The name suggests these Motors are universal that work with high torque and have different speed features. These Motors use electromagnets as the stator that produces a magnetic field. These Motors are generally lightweight and compact and work at a high speed. Usually, it is used in household appliances and featured with portable power equipment and tools. You can easily control and operate them with its tapped coils.

2. What are the examples of AC and DC?

AC defines Alternating Current and DC is defined as Direct Current. Usually, these Currents are referred to with the voltages. Everything that is powered with the battery and operates on an AC adapter uses DC Current. Such appliances are cell phones, flashlights, vehicles, TVs, etc. However, AC cannot be stored in the batteries as these do not supply energy because of changing polarity. In AC, the positive half will cancel out the negative half, which can damage the appliance battery with time. Hence the final conversion is made to DC Current.

3. What is Static Electricity?

Static electricity is generated by the imbalance occurring between the electric charges in a body (the negative and the positive charges on a body). This imbalance in the charge is created by some external physical means. The most common reason for static electricity is the contact between 2 solid objects. In an atom, the protons do not move and the only motion of electrons generates electric charge noticed in static electricity. Electrons of an atom are very loosely held which states that they can be exchanged through contact like rubbing. These charges can produce upon the surface of an entity until they find a way to be dismissed or discharged. An electric circuit is one of the ways that discharges the electrons and this is why thunder and lightning strike occurs. Static electricity is the electric field that is created due to the stationary charges in an atom. The surface of the material has some electric charges which mix with the static electricity on it. The static charges might come on the surface of the material by contact with 1 of the most charged bodies or through extra ions present in the air.

4. How is Alternating Current produced?

Alternating Current is a Current that alters its magnitude and polarity at periodic intervals of time. It can be generated by devices called alternators and by additional methods with the help of numerous circuits. The most common way of developing an Alternating Current is by operating a basic single coil AC generator. A basic single-coil AC generator consists of 2 pole magnets and a 1 loop of wire carrying a rectangular shape. In this kind of device, the AC generator uses Faraday’s principle of electromagnetic induction, where it transforms mechanical energy into electrical energy. Alternating Current is provided to components of the gear using three different wires. Each wire has its importance and is-

  • The total power is transferred by the first hot wire.

  • The second neutral wire which is joined to the earth supplies a return route for the Current in the first hot wire. 

  • The third wire that is also joined to the earth is linked to the metallic parts of the gear. This is done to remove the electric shock dangers.

5. What are the different types of resistors?

A resistor is a tolerant electrical component with 2 ends that are used for either limiting or controlling the flow of electric current in an electrical circuit. Resistors can be found in various shapes and sizes, but the most standard kinds that are known are through-hole and surface mount. A resistor might be a static, standard resistor, special, or a combination of several variable resistors. Different types of resistors are-

  1. Linear Resistors- Linear resistors are resistors that deal change with change in the involved temperature and voltage. There are 2 types of linear resistors:

    1. Fixed Resistors- Fixed Resistors are resistors that have a precise value and these values cannot be modified. For Example- Carbon composition resistors, Thin film resistors, etc

    2. Variable Resistors- Variable resistors are resistors that do not have a precise value and the values can be changed with the use of a dial, knob, and a screw. Variable resistors are resistors that have varied applications in the field of radio receivers for controlling volume and tone. For Example- Rheostats, Potentiometers, etc.

  2. Non-linear Resistors- Non-linear resistors are resistors that deal with changes in a circuit according to the temperature and voltage applied. Non-linear resistors do not depend on Ohm’s Law. For Example- Thermistors, Photoresistors, etc.