How To Tell Dynamo and Generators?

A dynamo is a machine that uses mechanical energy to convert it into direct current. Whereas the generator converts automatic rotation into alternating current. So, it’s different in the output.
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Dynamos and generators are the words you often hear people using. This is because both operate to convert mechanical rotation to electric power. But their construction and work are different. To understand the difference between them, you should first understand the structure and working of a dynamo.

What is Dynamo?

A dynamo is a machine that uses mechanical rotation to convert it into a direct current (Woodward, 2018). It works on the phenomenon of electromagnetism. At first, you need an automatic power source to provide mechanical energy.

For a dynamo, the turbine provides a power source through the fall of water on it. This causes the turbine shafts to rotate. The turbines can also include a wind turbine, gas turbine, or a steam turbine.

On the other side of the shafts, they connect to a generator. The generator, as a result, creates power by converting that mechanical energy into electrical energy.

What is the working principle of a Dynamo?

A dynamo works on the principle of Faraday’s law of Electromagnetic Induction. In practical terms, this states that (Prakash, 2007):

“If we take a wire and move it to-and-fro in a magnetic field, the current will produce.”

The magnets provide the magnetic field that places on the sides of the wire.

The flow of current is due to the movement of electrons. The process is that when the wire moves back and forth in a magnetic field, the field forces the electrons to move. The action is from one end to the other end of the wire—this movement of the electrons from one side to the extra call an electric current.

What are the parts?

Following are the main parts of a Dynamo:


The dynamo provides stationary magnets to produce a dense magnetic field. These static magnets call Stator.


A rotating magnet provides between the Stator to cut through the magnetic field. This rotating magnet is called the rotor.

The distortion of the magnetic field creates magnetic flux. As per Faraday’s law, the change produces electricity.

We can understand the formation of the magnetic field by using lines of the magnetic flux. Which can see by putting some iron filling between the area. The iron filings will align themselves in the pattern of the magnetic field.


The dynamo produces a current in only one direction, i.e., direct current. The commutator needs to ensure such. As the current flows through the wire, the dynamo reverses the direction of the wind. In each turn, the commutator acts as a rotary switch. It disconnects the power during the changed current part. This results in the production of direct current.


What is a solenoid, and why is it preferred in a dynamo?

A solenoid is an electromagnet that is tubular in shape. It creates by coiled wire. The solenoid is not made up of a permanent magnet. Rather it a copper or aluminum wire coiled around an iron core.

Each coil magnetizes beforehand by energizing it with some power. Due to the mesh of the ring around the magnet, more flux creates. This results in the production of more current. Even a small solenoid can create a powerful magnetic field.

How to find strength?

The strength of the generator depends on three main things:

  1. The conductor’s length in the magnetic field is denoted by l.
  2. The velocity with which the conductor moves in the field is denoted by v, i.e., speed of the rotor).
  3. Strength of the magnetic field denoted by B.

Gain more strength of the generator, many wires arrange to make them in a coil form. This results in the formation of a powerful flow of electrons. , the strength calculates as follows:

e = B x I x v

What mean by self-excitation in a dynamo?

It is a kind of excitation in which the main poles’ magnetic field makes stronger by exciting it. The excitation does by the current that supplies to the windings of the central bar from the rotor.

When a self-excited dynamo start, the electromotive force produces the initial current in the field winding. This emf induces in the armature winding by the residual magnetic field of the main poles.

What is the difference between a dynamo and a generator?

Type of current:

A dynamo is a machine that uses mechanical energy to convert it into direct current and alternating current. In contrast, the generator converts automatic rotation into alternating current. So, it’s different in the output in some places.

While the dynamo produces a direct current and alternating current, the generator produces an alternating current.

Working principle:

Both work on the principle of Faraday’s law of electromagnetic induction. They differ in their process. In a dynamo, a magnet rotates inside the influence of another magnet’s magnetic field. The Stator produces a dense magnetic field. The rotor distorts the magnetic field and results in electricity.

Whereas, in a generator, the conductor-coil fixes, and the magnet rotates around it. This cuts a uniform magnetic field. And the voltage generates in that conductor.

Current conversion:

In a dynamo, a commutator uses to convert the produced alternating current to the direct current. While the alternating current is what need in a generator. It can change as per need. For this, a solid-state AC to DC converter uses (Brainly, 2019).

Origin of the word:

The word ‘generator’ is a general term for anything that produces electrical energy. The generator can be a direct current generator or an alternating current generator. At the same time, a dynamo is the precursor of a generator, many energy devices can drive that. It has both a direct and alternating current as well. The alternating current producing machine is called an alternator.


It is a preferred practice to use generators for power generation. A dynamo is less reliable and less efficient than a generator due to its complicated construction.


The dynamo provides the facility of self-excitation. Whereas no such thing as excitation exists in a generator.


I’m sure that after going through this article, the difference had become clear to you. In conclusion, a dynamo is a DC generator that only produces a direct current. Whereas when the word ‘generator’ use, it can mean a DC generator or an alternator.

Do let me know if you have any other queries in the comment section below. We would love to know your thoughts.

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Hey all, I'm Baymax Yan, working at a generator manufacturer and Having more than 15 years of experience in this field, and I belives that “learn and lives.” The sure thing is that I can often help my work. So I have created the blog to share all my knowledge with you. Hope my sharing helps!

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