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The image shows the main components that underlie the application of the principle of the electric motor.

In order for the unseen and non-palpable electrical energy to be transformed into mechanical power, moving the rotor and caloric energy, respectively the heat released by the engine, two magnets are used, with the northern magnetic pole, in the upper left part, and another with the southern magnetic pole, in the upper right part, marked with two rectangles with the corners from the center of the  image rounded, filled with texture of oblique and parallel lines.

So, the motor consists of two essential components:

  • There’s a permanent magnet (or magnets) around the edge of the motor case that remains static, so it’s called the stator of a motor.
  • Inside the stator, there’s the coil, mounted on an axle that spins around at high speed—and this is called the rotor. (Bibliography 1)

A magnetic field is formed between the two magnets, the space in which the magnetic waves propagate, in the center of which is a rotor with current carrying conductor, which also determines an electric field.

The two fields form an electromagnetic field, produced around electrically and magnetically charged bodies.

The current carrying conductor is a rotor or the metal rod, a component through which the current passes, due to the copper material of the wire, rendered by a thickened line that outlines a square, between the two magnets above, then descends as two parallel lines, passing through the two slip rings and ends at the right end, outlining a vertical rectangle, with the right side made of a broken, jagged line.

This jagged side on the bottom right represents the load, or frame on which the energy-conducting copper wire is rolled.

The metal rod or axle rotates, when it is charged by electric current, in the direction of magnetic polarization.

The slip rings on the conductor are highlighted by two horizontal and parallel rectangles, in the central bottom, embossed.

At the right ends of the slip rings are coal brushes, usually graphite, which are electrical contacts that direct the electric flow through copper, between the coil load and the rotor, rendered as two short rectangles, embossed.

The coal is used as a buffer in the electrical circuit, attenuating the force of the electric current in contact with the coil, so as not to ignite in a short circuit and so that the copper wire can withstand a continuous flow for a longer time.

General information

The invention of the engine, be it internal combustion, steam or electric, has brought important changes in people’s lives. If until the advent of the steam engine in the 18th century people used the force of wind, water, and the power of domestic animals to travel and transport goods, with the advent of engines, transport became easier and faster. At the same time, changes have occurred in the infrastructure of roads and access routes, for example, railways are emerging.

Every engine is based on the law of energy conservation, namely that nothing is created, nothing is lost, but transformed. Therefore, any engine operates on the principle of transforming or converting an   energy source   into mechanical energy. 

Thus, the electric motor is an instrument through which the electricity converts into mechanical energy, most commonly, in rotational motion.  

The electric motor consists of two main parts: a fixed part called a stator and a movable part called a rotor. The fixed part, the stator, includes the engine housing, the ferromagnetic armature and the power terminals, and the rotor includes the rotor shaft and armature supporting the rotor winding, i.e. one or more coils.

One of the important classifications of their electric motors is given by the type of electric current they use to operate. Thus, we distinguish DC motors and AC motors.

It is the continuous current that does not change its direction, the electrons move in one direction, from the negative battery terminal to the positive battery terminal, the batteries being a known source of such current.

In the case of alternating current, electrons change direction at a regular interval. At the sockets in our homes we encounter this type of current, where the direction of electrons changes 50 times per second.

The DC engine was invented by Zenobe Gramme in 1873 and has many applications, from motor toy cars to powerful towing machines, e.g. locomotives.

AC engines are used in applications where the requirement is that the engine speed does not vary greatly in relation to the load, for example, fans or lifting machines, lifts.

Did you know that engines have two principal functions, namely drive and braking? When we’re in the elevator of a building and we go up from the ground floor to some floor, the elevator motor drives the cab, and when we get off, it breaks it. Thus, the gravitational force does not cause the free fall of the cabin.

The fastest engine in the world is an electric one and reaches 104,000 revolutions per minute. As a comparison, the engine of a regular car reits up to about 7,200 revolutions per minute.

The electric motor is much more efficient compared to the diesel or cell Otto, meaning the petrol engine. In internal combustion engines, heat losses are high. Some of the heat goes to the cooling systems, they don’t let the heat engine overheat. Another part of the heat generated by burning the fuel is fired through the exhaust system, that is to say on the muffler. Only the third part of the heat is converted into useful mechanical work.

If the efficiency of the internal combustion engines varies between 20% and 45%, a well designed electric engine may reach an efficiency of approximately 90%.


  1. How does electromagnetism make a motor move?, available at https://www.explainthatstuff.com/electricmotors.html accessed on 28.07.2020
  2. http://www.b365.ro/11-lucruri-interesante-despre-motoarele-electrice_259778.html
  3. https://ro.wikipedia.org/wiki/Motor_cu_abur
  4. http://cursuri.flexform.ro/courses/L2/document/ClujNapoca/grupa7/Peter_Erzsebet/site/energie.html
  5. https://ro.wikipedia.org/wiki/Legea_conserv%C4%83rii_energiei
  6. https://fizicaelucidata.wordpress.com/2016/03/30/nimic-nu-se-creeaza-nimic-nu-se-pierde-totul-se-transforma/
  7. https://ro.wikipedia.org/wiki/Motor_electric

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