The Origins of the Electromagnetism

 THE ORIGINS OF THE ELECTROMAGNETISM

Several efforts were made, during the 18th century, in the search for a connection between electricity and magnetism. At the end of century the story of the experiments with frog legs made by Galvani (1737-1798) which led Volta (1745- 1827) to manufacture a battery which was able to constantly produce electric current. The studies continued in the following century with Oersted. This Danish philosopher, physicist and chemist was born in 1777 in Ringkobing and died in 1851 in Copenhagen. His discoveries shaped post-Kantian philosophy and advances in science during the late 19th century.

In 1801, Ørsted began a series of European trips in which he eventually met Ritter, a German physicist who believed in the existence of a relationship between electricity and magnetism. From then on, Ørsted began his tireless research into the relationship between these two phenomena. In 1820, Ørsted recorded that when a compass was brought close to a wire running with an electric current, the compass needle moved so as to position itself perpendicular to the wire; when the current was reversed, the needle turned 180°, becoming perpendicular to the wire again. This was the first demonstration that there was actually a connection between electricity and magnetism - the Ørsted effect. Thus, electromagnetism was born.

MICHAEL FARADAY

Michael Faraday, the greatest researcher in the field of electricity and magnetism in the 19th century worked for 10 years to try to prove that a magnet could induce electricity. In 1831 he achieved his goal by using 2 coils of wire wound on opposite sides of an iron ring/core. 

- First he passed current through the first coil so that the ring of iron to become magnetised;

- Then he extended a wire from the 2nd coil to the needle of a compass at a distance of one metre;

- As soon as the first circuit was connected, Faraday observed a momentary deviation of the compass needle and the immediately returned to its original position;

- When the primary current was switched off, a similar deviation of the compass needle opposite direction.

Based on this observation, Faraday showed that changes in the magnetic field around the first coil are responsible for inducing current in the second coil.  And so, in the same year, he developed Faraday's law of induction.

JAMES CLERK MAXWELL

Scottish physicist known for his formulation of the electromagnetic theory.  He is considered by most modern physicists as the 19th century scientist who had the greatest influence on the physics of the 20th century. Indeed, in 1873 he wrote his famous "Treatise on Electricity and Magnetism", in which Maxwell stated that his main task was to convert Faraday's physical ideas into a mathematical form. 

This attempt to translate physical laws into mathematical relationships led him to obtain Maxwell's famous equations.

Maxwell's theory predicted that electromagnetic waves could be generated in the laboratory, a possibility demonstrated by Heinrich Rudolf Hertz in 1887, eight years after Maxwell's death. The resulting radio industry with all its applications, therefore, has its origins in Maxwell's Maxwell's publications.

EXPERIENCE: ELECTRIC MOTOR

The principle of operation of this motor is:  when current flows through the coils a magnetic field is created that tends to align with the magnetic field produced by the permanent magnet, this causes rotation. 

However, when the current flow is cut off at the end face where the varnish or enamel has not been removed or enamel has not been removed, the rotation is completed, reconnecting the circuit and causing a new rotation. 

This continued process produces an approximately constant rotation, bearing in mind that the effects of the magnetic field are different when the coil passes in the horizontal position and when it passes in the vertical position.

DAILY LIFE

Electromagnetism plays a very important role in our daily lives.

In the domestic environment we can observe the use of electromagnetism:

- in lighting;

- in kitchen appliances;

- in air conditioning systems etc.

All these common objects use or create electromagnetic fields.

In the industrial field electromagnetism is used in at least one step in almost all instruments used.

In medicine, electromagnetism plays a fundamental role in advanced medical equipment.

To transmit information from a source to a receiver, using radio waves or  microwaves. In the case of mobile phones, sound is converted into electromagnetic energy and by using radio transmitters, this energy is transferred to the receiver where it is transformed back into sound waves.

In conclusion, electromagnetism is fundamental to our lives and is a major factor in the evolution of technology. 

André Leão n⁰2 11⁰A

João Silva n⁰11 11⁰A

José Antunes n⁰12 11⁰A

Laura Barreiro n⁰14 11⁰A