Types of electric motors
In 1831 Michael Faraday made important discoveries that proved that indeed a magnetic field can produce an electric current, but provided that something was varying in time. Thus he discovered:
C being a closed curve, which normally coincides with a material circuit (a mesh of a circuit, for example), but it can also be a simple imaginary curve. This e.m.f. is called an induced e.m.f.
– The negative sign is crucial in Faraday’s law since it indicates the direction of the induced current. The consequences of this sign are expressed in Lenz’s law, discussed below.
Considering a counterclockwise direction of travel of the loop, the vector a normal to a surface resting on it points towards us. The magnetic flux is equal to the value of the field for the area where it is located, which is not the whole loop, but only the area occupied by the field.
In the case where the coil is entering the field (v > 0), the induced current is negative, i.e. it goes clockwise (the opposite of the assumed one). If it is exiting, it is positive, i.e. counterclockwise (the same as the assumption).
What is an electric motor
The electric motor is a device that converts electrical energy into mechanical rotational energy by means of the action of the magnetic fields generated in its coils. They are rotating electric machines composed of a stator and a rotor.
They are used in many sectors such as industrial, commercial and private installations. They are widely used in fans, vibrators for cell phones, water pumps, electric means of transport, household appliances, angle grinders and other electric tools, disk drives, etc.
Direct current or direct current comes from batteries, solar panels, dynamos, power supplies installed inside appliances that operate with these motors and rectifiers.
Alternating current can be taken for use in electric motors either directly from the mains, alternators of emergency power plants and other sources of two-phase or three-phase alternating current such as power inverters.
How an electric motor works
Electromagnetism encompasses a variety of real-world phenomena such as light. Light is an oscillating electromagnetic field that radiates from accelerated charged particles. Apart from gravity, most forces in everyday experience are a consequence of electromagnetism.
The fundamentals of electromagnetic theory were introduced by Michael Faraday and first fully formulated by James Clerk Maxwell in 1865. The formulation consists of four vector differential equations relating the electric field, the magnetic field and their respective material sources (electric current, electric polarization and magnetic polarization), known as Maxwell’s equations, which have been regarded as the “second great unification of physics”, the first being by Isaac Newton.
Electromagnetic theory can be divided into electrostatics – the study of interactions between charges at rest – and electrodynamics – the study of interactions between charges in motion and radiation. The classical theory of electromagnetism is based on the Lorentz force and Maxwell’s equations.
Characteristics of an electric motor
An electric motor is a machine that has the ability to transform or convert electrical energy into mechanical energy. It does this thanks to the action of the magnetic fields generated by its coils.
But, if we focus on the motor itself, we can say that it always works in the same way: through the interaction between sinusoidal currents and a magnetic field, which generates force or energy within it. That is to say, they start from the principle of electromagnetic induction which indicates that when a conductor is in interaction with the magnetic flux lines and between them there is a movement, a voltage is induced in the conductor which in turn being in a closed circuit will generate the circulation of an electric current and consequently the induction of a magnetic field that will interact with the existing one causing a torque and movement of the same.
However, in general terms, we can say that electric motors offer very good autonomy, especially when they are complemented with accumulators and batteries of high capacity and durability.