What is electromagnetism?

We explain what is electromagnetism, its applications and experiments that were performed. Also, what is it for and examples.

1. What is electromagnetism?

Electromagnetism is the branch of physics that studies the relationships between electrical and magnetic phenomena , that is, between the magnetic field and the electric current.

In 1821 the fundamentals of electromagnetism were made known with the scientific work of the British Michael Faraday, which gave rise to this science . In 1865 the Scotsman James Clerk Maxwell formulated the four “Maxwell equations” that fully describe electromagnetic phenomena.

2. Electromagnetism Applications

Electromagnetic phenomena have very important applications in disciplines such as engineering, electronics , health , aeronautics or civil construction, among others. They appear in daily life almost without realizing , as for example, in compasses, speakers, bells, magnetic cards, hard drives, to name just a few.

The main applications of electromagnetism are used in:

• the electricity
• the magnetism
• The electrical conductivity and superconductivity
• Gamma rays and x-rays
• The wave electromagnetic
• Infrared, visible and ultraviolet radiation
• The microwave and microwave

3. Experiments on electromagnetism

Through simple experiments it is possible to understand how some of the electromagnetic phenomena work, such as:

• The electric motor Below is an experiment that demonstrates a basic notion of the operation of an electric motor. For that, the following elements are needed:
  • A magnet
  • A battery AAA
  • A screw
  • A piece of electrical cable 20 cm long
• First step. Support the tip of the screw on the negative pole of the battery and rest the magnet on the screw head. You can see how the elements attract due to magnetism.
• Second step. Connect the ends of the cable with the positive pole of the battery and with the magnet (which is together with the screw, on the negative pole of the battery).
• Outcome. The battery-screw-magnet-cable circuit is obtained through which an electric current flows through the magnetic field created by the magnet, and it rotates at high speed due to a constant tangential force called “Lorentz force”. On the contrary, if you try to join the pieces by reversing the poles of the battery, the elements repel.
• The ” Faraday cage “. Below is an experiment that allows us to understand how electromagnetic waves flow in electronic devices. For that, the following elements are needed:
  • A portable radio that runs on batteries or a cell phone
  • A metal grid of holes not larger than 1 cm
  • A pliers or scissors to cut the rack
  • Small pieces of wire to join the metal grid
  • Aluminum foil (may not be necessary)
• First step. Cut a rectangular piece of metal grid 20 cm high by 80 cm long, so that a cylinder can be assembled.
• Second step. Cut another circular piece of metal grid 25 cm in diameter (it must have a sufficient diameter to cover the cylinder).
• Third step. Join the ends of the metal grid rectangle so that a cylinder forms and secure them with wire pieces.
• Fourth step. Place the radio on inside the metal cylinder and cover the cylinder with the metal grid circle.
• Outcome. The radio will stop sounding because electromagnetic waves from outside cannot pass through the metal .
  If instead of a turned on radio a cell phone is entered and that number is called to make it ring, it will also happen that it will stop ringing. In case that does not happen, a thicker metal grid and smaller holes should be used, or wrap the cell phone in aluminum foil. Something similar occurs when talking on the cell phone and entering an elevator, which causes the signal to be cut is the effect of the “Faraday cage.”

4. What is electromagnetism for?

Electromagnetism serves to manipulate the energy that human beings use to meet their needs. Many instruments that are used daily work due to electromagnetic effects . The electrical current that circulates through all the connectors of a house, for example, grants multiple uses such as the microwave oven, the fan, the blender, the television , the computer , etc. that work due to electromagnetism.

5. Magnetism and electromagnetism

Magnetism is the phenomenon that explains the force of attraction or repulsion between materials . While there are materials with powerful magnetic properties, that is, they function as a strong magnet such as nickel and iron, all materials are influenced to a greater or lesser extent by the presence of a magnetic field.

Electromagnetism involves those physical phenomena that are produced from electric charges, at rest or in motion , that give rise to magnetic fields and that produce effects on gaseous , liquid and solid elements .

6. Examples of electromagnetism

There are numerous examples of electromagnetism and among the most common are:

• The ringer. It is a device capable of receiving an audible signal when you press a switch. It works through an electromagnet that receives an electric charge , which generates a magnetic field (a magnet effect) that attracts a small hammer that hits the metal surface and emits the sound .
• The magnetic levitation train. It is a means of transport that is supported and propelled by the force of magnetism and by the powerful electromagnets located in its lower part, unlike the train driven by an electric locomotive that runs on rails.
• The electric transformer It is an electrical device that allows to increase or decrease the voltage (or voltage) of an alternating current.
• The electric motor It is a device that converts electrical energy and produces movement by action of the magnetic fields that are generated inside, that is, it produces mechanical energy.
• The dynamo It is an electric generator that uses the energy of a rotating movement and transforms it into electrical energy.
• The microwave. It is an electric furnace that generates electromagnetic radiation that vibrate the molecules of water in the food, which produces heat quickly and can cook food .
• Magnetic resonance It is a medical examination that obtains images of the structure and composition of an organism. It consists of the interaction of a magnetic field created by a computerized machine (which works like a magnet) and the hydrogen atoms contained in the body of the person. These atoms are attracted by the “magnet effect” (by the machine) and generate an electromagnetic field that is captured and represented in images.
• The microphone. It is a device that detects acoustic energy (sound) and transforms it into electrical energy. It does so through a membrane (or diaphragm) that is attracted by a magnet within a magnetic field and that produces an electric current that is proportional to the sound received.
• Planet Earth. Our planet works like a giant magnet due to the magnetism effect that is generated in its nucleus (formed by metals such as iron, nickel). The Earth is a great conductor of energy through the poles (North Pole and South Pole) that correspond to a negative and a positive pole. When magnetized elements with a different charge (one positive and one negative) are approached, they attract each other while when two elements that have the same charge approach, they repel. That magnetic core interacts with the Earth’s rotation movement and together they generate a stream of energetic particles, that is, a magnetic field on the Earth’s surface that repels harmful solar radiation.

7. History of electromagnetism

Electromagnetism was consolidated as a science in 1821 but, nevertheless, there are vestiges of electromagnetic phenomena dating back to previous centuries, for example:

• 600 a. C. The Greek Tales of Miletus observed that by rubbing a piece of amber, it was electrified and was able to attract pieces of straw or feathers.
• 1820. The Danish Hans Christian Oersted conducted an experiment that, for the first time, united the phenomena of electricity and magnetism. It consisted of bringing a magnetized needle closer to a conductor through which an electric current circulated. The needle moved so that it evidenced the presence of a magnetic field.
• 1821. The British James Clerk Maxwell made known the fundamentals of electromagnetism, which gave it formal origin as a science.
• 1826. The Frenchman André-Marie Ampère developed the theory that explains the interaction between electricity and magnetism, called “electrodynamics.” In addition, he was the first to name the electric current as such and to measure the intensity of its flow.
• 1865. Scottish James Clerk Maxwell formulated the four “Maxwell equations” that describe electromagnetic phenomena.