In physics, electricity is a generic term that encompasses a whole set of phenomena that are the manifestation of the presence of a movement of electric charges. We can apply the term electricity to phenomena known as lightning or static electricity but also to other such as the electromagnetic field or electromagnetic induction. The word also serves to designate the branch of physics that studies electrical phenomena and their applications.
In the following sections we will study electricity from a physical point of view…
The Joule effect, also called Joule's law, is the thermal manifestation of electrical resistance. If electricity circulates in an electric conductor, a part of the kinetic energy of the electrons is transformed into heat due to the shock that the electrons experience with the molecules of the conductor through which they circulate, which increases the temperature of the conductor. It is named in honor of the English physicist James Prescott Joule.
Definition of the Joule effect:
The amount of heat energy produced by an electric current is directly proportional to the square of…
The electric motor is an electrotechnical machine that converts electrical energy into mechanical energy. That is, when the electric motor is connected to the proper power source, it begins to rotate, which also begins to rotate the machine or the machine associated with it. That is, it works inversely to the electric generator, which produces electrical energy with mechanical energy.
The electric motor was made possible thanks to the discoveries of Franz Ernst Neumann and James Clerk Maxwell. His discoveries were published in the years 1841 and 1873.
The electric motors can be…
A direct current motor (DC motor), or simply a continuous motor or direct current motor, is a rotating electric malternating currenthine that transforms electrical energy in the form of direct current into mechanical energy through electromagnetic interalternating currenttions.
Virtually all electric motors are reversible, that is, they can transform mechanical energy into electrical energy functioning as dynamos. direct current motors base their operation on the Lorentz law, also called Laplalternating currente's law when it is applied to a conductor, as is the case of motors. Applications…
An electric generator is a machine that transforms rotational mechanical energy into electrical energy. In this sense, it works in the opposite sense of how an electric motor works.
An electric generator is any device capable of maintaining an electrical potential difference (voltage) between two points, called poles or terminals. Electric generators are electrical machines designed to transform mechanical energy into electrical. This transformation is achieved by the action of a magnetic field on the electric conductors arranged in coils on a sheet metal frame. If a relative movement…
In some applications, doubts arise as to whether it is better to use an electric motor or to use a thermal motor. One of the important elements in making this decision will be to know the differences in energy efficiency.
Main problems of thermal motors:
- Rising prices of fossil fuels combustibe (oil, coal, etc.)
- Scarce projections of evolution in an immediate future.
- Emission of greenhouse gases.
- Not reversible, when braking, can not generate power.
Main advantages of electric motors:
- You are a clean alternative if we…
The electric current is the flow of electric charge passing through a material per unit of time. Moving electrical charges produce a magnetic field.
It is called electrical charge to the physical property that possess certain subatomic particles (like the protons and the electrons). This property manifests manifested through the forces of repulsion and attraction that exist between them by means of electromagnetic fields. Protons have a positive charge and negatively charged electrons. This assignment of charges was performed arbitrarily.
Anyway, when we talk about electric current,…
An electromagnet is a type of magnet in which the magnetic field is produced by the flow of an electric current. If the flow of electrical current also disappears magnetic field disappears and the effect arising. Characteristics of electromagnets
The electromagnet is a simple piece of metal wire wound in a coil. A cylindrical coil with the wire coiled helix-shaped (like a corkscrew corkscrew-shaped) generally named solenoid; a solenoid would be a closed toroid.
May occur if stronger magnetic fields within the coil becomes a core of a ferromagnetic or paramagnetic material,…
The universal motor is a type of electric motor that can operate both with direct current and with single-phase alternating current.
Its constitution is similar to that of a direct current series motor, although with some modifications:
The polar nuclei, and the entire magnetic circuit, are built with silicon iron plates isolated and stacked to reduce energy losses by parasitic currents. These currents occur because of magnetic flux variations when connected to an alternating current network.
It has a lower number of turns in the inductor to not magnetically saturate…
In this website we try to explain the operation of the main types of engines from a theoretical point of view. We present schematically the parts, operating cycles and characteristics of the following types of engines:
- The thermal engine or internal combustion engine. Inside the thermal engines we explain the gasoline engine (or otto engine) and the diesel engine).
- The electric motor. This engine has undergone a great evolution throughout history and right now is one of the most used types of engines and with more projection of the future. We will analyze direct current…
A motor or motor is a machine designed to convert a form of energy into mechanical energy . An engine can be classified into a category according to two criteria: the form of energy it accepts to create movement and the type of movement it produces.
As a general rule, engines have an axle, which in rotary offset and through mechanical devices such as drive gears. The exceptions are rocket motors and linear motors . Nowadays, combustion engines…
The galvanic cell is a device consisting of two different metals connected by means of a salt bridge or a porous disk located between each half cell. It receives its name in honor to Luigi Galvani.
The voltaic cell, invented in 1800 by Alessandro Volta is similar to the galvanic cell. These discoveries paved the way for electric batteries.
The metal of a galvanic cell dissolves in the electrolyte at two different speeds. The metals become positive ions in dissolving and the electrons remain in the undissolved part. As a result, the metal acquires a net negative charge as the electrolyte…
The conversion of electrical energy into mechanical energy by means of electro-magnetism was first demonstrated by the British scientist Michael Faraday in 1821. In his pilot he made the end of a free-hanging contact conductor with a pool of mercury in the that a permanent magnet was placed. At the moment when a current flows through the conductor, the driver performs a rotary movement around the magnet. In this way we obtain kinetic energy.
This electric motor is the simplest version of a homopolar motor. An improved form of this is the Barlow wheel. Due to their primitive construction,…
The armature is the part of an electric machine, magnetically coupled to the inductor, where an electromotive force is generated by induction.
The armature is the rotor in DC machines and the stator in synchronous AC machines.
The term induced term varies depending on the context in which it is used. It is usually linked to the electricity sector, electric machines and motors. Electric machines and motors
If we are talking about electric machines and electric motors. In this context the armature is the part of the rotating machine where the transformation of electrical…
Diesel engines have several advantages over other internal combustion engines: Advantages related to diesel engine fuel
The fuel of a diesel engine has a higher energy density and a smaller volume of fuel is required to perform a specific amount of work.
Diesel engines inject fuel directly into the combustion chamber, have no air intake restrictions other than air filters and intake pipes and have no vacuum in the intake manifold to add parasitic load and pump losses to push the pistons down against the vacuum of the intake system. Cylinder filling is aided by atmospheric…
An asynchronous motor is an electric motor powered by alternating current. It is, therefore, what we call an AC motor. This type of engine is also known as an induction motor.
The asynchronous motor is based on the currents induced in the rotor from the rotating magnetic field of the stator. That's why it's called an induction machine. As to be able to induce an electric current in the rotor it is necessary that the rotor is subjected to a variation of the magnetic flux generated by the stator at the frequency of power, or synchronism, the rotor is demagnetized when it reaches the synchronism,…
Altern current motors are electric motors that are powered by alternating current. Electric motors convert electrical energy into mechanical rotation energy through the mutual action of magnetic fields.
There is a wide variety of altern current motors, among which the following basic types stand out:
- The universal motor that can also be direct current.
- The synchronous motor. In this type of electric motor the speed of rotation is constant and depends on the frequency.
- The asynchronous motor. It is a three-phase motor.
In some cases, such as…
The stator is the fixed part of an electric machine. By electric machine we refer to both electric motors and electric generators. The moving part of an electric motor is called a rotor.
In AC machines the stator is generally in the form of a cylindrical tube, with a certain wall thickness. A based on stacked crowns of magnetic sheet with a toothed on its inner circle are formed the slots where the coils are housed. In the continuous current machines the stator is formed by a solid steel cylindrical frame. This frame has polar poles or pieces with corresponding coils attached to it.…
The rotor is the component that turns on an electric machine. The same definition is valid whether the electric machine is an electric motor or an electric generator. The rotor together with its together with its fixed counterpart, the stator, form the fundamental set for the transmission of power in motors and electrical machines in general.
The rotor is formed by an axis that supports a set of coils wound on a magnetic core. This axis rotates inside a magnetic field created either by a magnet, an electromagnet or by passing through another set of coils, wound on some polar pieces.…
The Stirling engine applications can be divided into three main categories:
- Mechanical propulsion
- Heating and cooling
- Power generation systems
A Stirling engine is a thermal engine that works by cyclic compression and expansion of air or other gas, the working fluid. During the Stirling cycle there is a net conversion of heat to mechanical work. The Stirling cycle engine also operates in reverse, using a mechanical energy input to drive the heat transfer in a reverse direction (ie, a heat pump or refrigerator). Generation of electrical energy…
The electric motors can be distinguished between them according to the type of power supply:
- Electric motors of direct current. The DC electric motor can be, in turn, a permanent induction motor or a continuous induction motor. In addition to these more general classifications there are also other more modern types of engines such as stepper motors and linear motors.
- Electric motors of alternating current. The AC motor can be classified as universal motor, synchronous motor or asynchronous motor.
The classic division is between direct current (DC) and alternating…
Thermal energy is the form of energy possessed by any body that has a temperature above absolute zero. Macroscopically, thermal energy is an extensive amount and the amount of this energy that a body possesses is proportional to the temperature.
According to the second principle of thermodynamics, it is considered a degraded form of energy because not all thermal energy can be converted into mechanical energy. By contrast, any other form of energy has the potential to become more or less spontaneously thermal energy (such as mechanical energy by friction, electromagnetic energy by absorption…
Electric motors of direct current work thanks to the properties of the magnets and to the magnetic field that is generated when circulating an electric current by a conductor.
As we well know, the main characteristic of magnets is that they have a south pole (negative) and a north pole (positive). In two different magnets the poles of different sign attract each other and the poles of the same sign repel each other.
A linear motor is an asynchronous electric motor that has been developed so that instead of generating a rotating torque it generates a linear displacement. To get it distributes your stator and its rotor distributed differently.
The most common mode of operation is like a Lorentz actuator. In this mode the applied force is linearly proportional to the electric current and to the magnetic field
Linear motors are divided into two main groups:
- Slow acceleration linear motors used in Sky Train transport, Maglev, etc.
- Quick acceleration linear motors used in…
Traditionally, when we talk about motors, we usually refer to internal combustion engines or electric motors. However, there are other types of motor. Among these types of motor there are the physical power motors.
The so-called physical power motors are motors that take advantage of the kinetic energy or the potential energy of some element.
An example of power motors is found in hydro power plants. In this type of installation the potential energy of the water is used, which, when it falls, becomes kinetic energy and activates a turbine. In this way, a motor,…
The commutator is a component of an electric motor formed by strips of hard electrolytic copper with insulating material in the middle (formerly micanite, nowadays plastic). The assembly is insulated on the rotor shaft and the copper blades are connected to the anchor windings. Permanently installed carbon brushes make contact with the collector and provide power to the anchor windings.
A commutator is a rotary electrical switch in certain types of electric motors and electric generators that periodically changes the direction of the current between the rotor and the external circuit.…
In physics, mechanical energy is the sum of potential energy and kinetic energy. This energy is associated with the movement and position of an object. The principle of mechanical energy says that in an isolated system where there is only a conservative force, then the magnitude of the mechanical energy is constant.
If an object moves in the opposite direction to the conservative force, then the potential energy increases. It would be the case of a rocket, the conservative force, in this case, it would be the force of gravity. If the velocity of the object changes, then its kinetic energy…
Foucault currents are the currents induced in masses of conducting metal that are immersed in a variable magnetic field or that, in motion, through a constant or variable magnetic field. In any case, it is the variation of the magnetic flux that generates these currents. The phenomenon was discovered by the French physicist Jean Bernard Léon Foucault in 1851.
In high frequency: using cores with magnetic materials that have low electrical conductivity (such as ferrite).
Foucault currents create energy losses through the Joule effect. More specifically, these currents transform…
The direct current is a type of electrical current on the flow direction of the flow of electric charge does not vary. The load flow occurs through a conductor such as a metal wire, but could also be established through a semiconductor, an insulator or even vacuum as in a cathode ray tube . In this type of electric current electrical charges always flow in the same direction, being a hallmark front alternating current. A synonym is unused direct current galvanic current.
The first commercial power grid, developed by Thomas Edison in the late nineteenth century, using direct current.…
The uses of the steam engine have been changing with the passage of time.
Initially, since the early eighteenth century, steam engines have been used to power a multitude of uses. At first, the steam engine was used as a piston pump. A piston pump is a hydraulic pump that generates movement in it by the movement of a piston.
Subsequently, from the years 1780 began to appear alternative engines. With the alternative motors a new use of the steam engine appears: to give power to the factories and to the industrial one. At the beginning of the 19th century, steam…
The series motor is a type of electric direct current motor in which the armature and the inductor debited or excitation are connected in series. That is why the excitation current or the inductor is also the current of the induced absorbed by the motor.
This type of direct current motor is also called the series excitation motor. The constitution of the electric motor in series is that of having all the elements of the circuit in series, induced windings and inductors. The series engine is characterized by having a high moment of rotation at start-up and its speeds very variable depending…
The endothermic engine, also known as internal combustion engine. The main characteristic of this type of alternative engines is that through the laws of thermodynamics it is able to take advantage of the energy contained in the fuel to obtain a mechanical work.
The endothermic engine is a type of alternative engine by the way of converting chemical energy into mechanical energy. The most popular endothermic engines are the Otto engine or gasoline engine that operates according to the Otto cycle and the diesel engine, which operates according to the diesel cycle. Meaning of the…
A spark plug is an electrical device that fits in the head of some internal combustion thermal engines and ignites compressed gasoline by means of an electric spark. It is used, therefore, in petrol engines with otto cycle.
The spark plugs have an isolated central electrode which is connected by a strongly insulated wire to a circuit of the ignition coil on the outside, forming, with a terminal connected to ground at the base of the plug, a spark gap inside the cylinder. How does a spark plug work? How is the spark generated?
As the electrons flow from the coil, a voltage…
The alternating current is a type of electrical current that is characterized by change over time, either in intensity or direction at regular intervals.
The voltage varies between maximum and minimum values cyclically, the value of positive voltage is half the time (semicicle semiperíode positive or positive) and the other half negative. This means that half the time the current flows in one direction, the other half the time the other way.
The most common way to curl follows a trigonometric function sine type, since it is the most efficient and practical to produce electricity…
The current carrying excitation winding in the stator generates a magnetic field, which is amplified by the iron sheet package and grouped into defined poles. The same happens in the winding of the armature coil downstream. Depending on how the poles are established, this magnetic field created by the stator of the universal motor causes the rotor to drag behind or push it in front of it. In this case, the coils must be inverted in each half revolution (for machines with a pair of poles), for which a switch is necessary.
Considering a "single pole" version, both magnetic fields are perpendicular…
The route of the Stirling engine throughout history begins in the early 1800s, in England. The hot air engines competed with the steam engine to provide mechanical power to the industrial machinery (in factories and mines) of the first industrial revolution.
Although steam engines had better characteristics than air machines, the air motor had the advantage of being less dangerous. This was due to the first realizations of steam engines suffered devastating boiler explosions. These explosions were due to the use of materials available at the time that were technologically poor.