Difference Between Alternator and Generator

Dhristi JEE 2022-24

What is the Difference Between Alternator and Generator?

An electrical generator is an alternator that converts the energy of mechanical to electrical energy in the form of alternating current. An alternator which is  linear or rotating in the armature with a stationary field of magnet is used in many fields. In principle any electrical AC generator can be called an alternator. But usually the term basically refers to small machines which are rotating and are driven by automotive and other internal engine combustion.

Generator and Alternator Difference

An alternator that uses a magnet which is permanent for its field  is called a magneto. Alternators in power stations generally are driven by steam turbines known as turbo-alternators. A very Large 50 or 60 Hz alternator of three-phase power plants generates most of the world's electric power. The power which is generated is distributed by electric grid power.


A conductor moving relative to a magnetic field develops an electromotive force, EMF in its law of Faraday's. This reserved EMF and its polarity moves under poles of magnetic polarity. We can say that typically a rotating magnet is known as the rotor turns which is within a set of stationary conductors wound in coils on a core of iron is known as the stator. The cuts of the field which is across the conductors generate an induced EMF that is electromotive force as the input of mechanical forces causes the rotor to turn. The magnetic fields induce a voltage of AC  in the stator windings since the currents which are present in the stator windings, vary in step with the rotor position because an alternator is a generator synchronous.

Difference Between DC Generator and Alternator

The generator is a device that converts power that is mechanical energy into power electrical for use in an external circuit. The electromagnetic generator was the first Faraday disk and it was invented in Britain by scientist Michael Faraday in 1831. The Generators which provide nearly all of the electrical power for grids.


The converse of energy which is  electrical and is into energy which is mechanical is done by a motor which is an electric motor and at times we can say the generator and motors have many similarities. Many of the motors can be mechanically driven to generate electricity frequently, that is they make manual acceptable generators.

Generator Alternator Difference

One of the major differences between the generator and alternator is that in alternator the armature which is stationary and the system of field rotates whereas in the generator armature rotates and the field is very stationary. The armature which we have discussed is the alternator which  is mounted on the element which is a stationary element known as the field and stator winding which is on a rotating element. While if we notice then the connection of a generator is just the reverse of it. The other differences which are between them are shown below in the comparison chart mentioned in the article's end.


The generator and the alternator both work on the principle of law of Faraday which is of electromagnetic induction. The induced generator which has both the direct and alternating current and the alternator produces only current which is alternating. The generator's rotor is placed inside the magnetic field which is stationary.


The magnetic field which is stationary is produced by the poles of the magnet. The rotor generally moves inside the field of magnet which later intersects the line of magnet of force which induces the wire current.


Every rotation which is  half of the rotor changes the direction of the current which later causes the current which is alternating. For getting the current which is alternating in nature the ends of the circuit are directly connected to the load. But for producing the current which is direct the ends of the wire are also connected to the commutator. The commutator converts the current which is alternating into direct current.

State the Difference Between Generator and Alternator

The generator which is synchronous or we can say Alternator is a machine for converting the power which is mechanical from a prime mover to an AC power of electrical at a specific frequency and voltage. The alternator which is Three-phase is used because it has many advantages of distribution. That can be said as the  generation and transmission. For the power which is in bulk generation a large alternator is used in the hydro, thermal and nuclear power stations.


The generator generally converts the energy which is mechanical into energy which is electrical or power. The generators working is based on the principle of Faraday's law of electromagnetic induction that is whenever the conductors cut the magnetic flux which EMF induces. This EMF causes the flow of current if the conductor is closed. The field which is a magnetic field and conductors are the two essential parts of generators.

Key Difference 

  1. A mechanics of  alternator which converts the energy which is mechanical from a prime mover into the AC on the other hand the generator converts the energy which is mechanical from the prime mover into an DC or AC.

  2. The induced alternator AC whereas the generator which causes both the AC and DC power. The generator which produces the current which is alternating which is converted into DC by the help of the commutator.

  3. The alternator has a magnetic field with a rotating field on the other hand the generator has a magnetic field which is a rotating field for the high voltage generation and the voltage which is low and stationary magnetic field is used.

  4. The alternator usually takes supply input from the stator whereas the generator takes input supply from the rotor.

What is an Alternator? 

An alternator is also an electric generator that is used for converting mechanical energy to electrical energy with alternating current. Alternators use a rotating magnetic field with a stationary armature. This is used because it is cheaper to do it this way and usage of anything else is too expensive. Alternators are usually referred to small rotating machines which are directed by automotive engines but sometimes bigger machines like AC electrical generators are also called alternators. 

Applications of an Alternator

  • Electric generators 

  • Radio generators

  • Marine alternators

Electric Generators

The definition of electric generator as defined by wikipedia is “In electricity generation, a generator is a device that converts motive power (mechanical energy) into electrical power for use in an external circuit”. There are many sources of these mechanical energies. Electric motors however are used for the reversal conversion of electric energy into mechanical energy. These electromagnetic devices are separated into two categories and they are dynamos and alternators. Dynamos give out direct current through a commutator but alternators generate alternating currents, just as the name suggests. 


Generators are functional because they contain a rotating part and a stationary part. Rotor is the rotating part of the generator and the stator is the stationary part of the generator.  One part of the electric generator starts the magnetic field whereas the other part has a wire through which it induces an electric current. These are the existing parts of the electric generators and this is how they work. 

Signal Generator 

A signal generator is also an electrical generator that generates electronic signals based on a variety of properties such as amplitude, frequency and wave shape. For electronic measurements, which are commonly used in designing, testing and repairing devices - these generated signals are used as a stimulus. Often, these generated signals are also used for aesthetic purposes. All the different kinds of generators have their own unique applications and properties but are used for various reasons. 

Types of Signal Generators: 

  • Functional generators

  • RF

  • Microwave signal generators

  • Pitch generators

  • Arbitrary waveform generators 

  • Digital pattern generators

  • Frequency generators 

FAQs on Difference Between Alternator and Generator

1. Explain alternators and generators in simple terms?

An alternator converts mechanical energy to electric energy whereas a generator is a mechanical device that converts mechanical energy to either AC or DC electrical energy. The major difference is that an alternator always gives an alternating current and a generator can either induce alternating current or direct current. The difference can be studied in the Vedantu website where all the information is available for free downloads. Students can make good use of these resources.

2. Explain Why Cars Use Alternators Rather Than Generators?

An alternator is said to be a type of generator which is electric used in modern automobiles to charge the battery and to supply the energy or we can say the power to the electrical system when its engine is running. With the availability of silicon affordable diode rectifiers and alternators were used instead.

3. Explain  the Difference Between Alternators?

The key differences which is Between Alternator & Generator is that the alternator induces the AC on the other hand  the generator causes both the AC and DC power. The alternator has a rotating field which is magnetic whereas the generator has a rotating field which is magnetic in nature for the high voltage generation and low voltage stationary field of magnet.

4. How can the car run without an alternator?

Alternators are the key element to help the car to run smoothly. Car is an automobile machine that needs power and energy to function. Alternators provide this exact energy to the car and give it the battery life that is required for driving short or long distances. However, a car can go for a very small distance without an alternator but it is not permanent so it is always recommended to search for a shop and get an alternator if your previous one in the car isn't functioning anymore.

5. How to understand the differences between alternator and generator?

Students can understand the difference between an alternator and a generator by drawing out a difference table. In this, they can list out various properties and qualities that each device differs from the other. They can write about the currents induced by both the alternator and generator separately and compare the difference between them. This way, they will remember better and will be able to answer well in the exam.

6. How to score full marks in this question?

Students should make sure to study the difference between alternator and generator and cover all the topics beforehand. They will find it easy to study if they take revision notes along with their preparation because it will be easier for them to revisit their notes when they want to do a quick revision. The concepts are all basic and easy to understand and many theoretical questions might be asked based on them so it is important to not skip these topics.

7. Where are alternators used?

Alternators are devices that induce electrical energy and they always have alternating current. Alternators are used in automobiles and cars to charge the batteries and to supply energy to fuel the engine. It gives the electrical power to the car engine when it has to run smoothly. Hence, alternators are used in care. Generators induce both alternating and direct currents so it is not used in automobile devices.

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