# Magnetism and Electromagnetism

## Georg Ohm

Before focusing his carreer on electricity, Georg Ohm went to school at at the Jesuits’ College at Cologne in 1817. He then focused his studies primarily on the theories and applications of current electricity. Ohm discovered  that the current flow through a conductor is directly proportional to thepotential difference (voltage) and inversely proportional to the resistance (I=VR). Ohm proved his discovery in two important papers in 1826, Ohm gave a mathematical description of conduction in circuits modeled on Fourier&apos;s study of heat conduction. These papers continue Ohm&apos;s deduction of results from experimental evidence and, particularly in the second, he was able to propose laws which went a long way to explaining results of others working on galvanic electricity. In the 1920s, it was discovered that the current through an ideal resistor actually has statistical fluctuations, which depend on temperature, even when voltage and resistance are exactly constant; this fluctuation, now known as Johnson-Nyquist noise, is due to the nature of charge. This thermal effect implies that measurements of current and voltage that are taken over sufficiently short periods of time will yield ratios of V/I that fluctuate from the value of R implied by the time average of the measured current; Ohm&apos;s law remains correct for the average current, in the case of ordinary resistive materials.

Alessando volta   became interested in electricity after reading about the history of electricity. Volta became a physicist and focused his studies on electrical currents. Volta discovered that electricity can be generated from metals. One of his most influential findings was the fact that electricity can be generated from metals. Volta was also a gifted inventor, and one of his greatest creations was based on the concept of metal-generated electricity--the voltaic pile. For his many achievements in the study of electricity, the unit of force in electrical current--the volt--was named in Volta&apos;s honor.

## Charles-Augustin de Coulomb

Coulomb focused on a few parts of the electron wave function, increasing the efficiency of intense field processes as multiphoton double ionization which is a process of formation of doubly-charged ions when laser radiation is exerted on neutral atoms or molecules. He also did research on friction of machinery, on windmills, and on the elasticity of metal and silk fibres. Coulomb’s law states that the force between two electrical charges is proportional to the product of the charges and inversely proportional to the square of the distance between them. Coulomb invented sensitive apparatus to measure the electrical forces involved in Priestley’s law. He also established the inverse square law of attraction and repulsion of unlike and like magnetic poles, which became the basis for the mathematical theory of magnetic forces.Modern Uses: Austin,Texas uses a metro rail that is kept on a track using electromagnetic force that can be calculated using coulombs law.

## Andre-Marie Ampere

Ampère engaged in a lot of scientific inquiries during years leading up to his election to the academy. He engaged in topics such as mathematics and philosophy to chemistry and astronomy. Developed a mathematical and physical theory to understand the relationship between electricity and magnetism known as amps. Ampère’s law, which states that the mutual action of two lengths of current-carrying wire is proportional to their lengths and to the intensities of their currents. He discovered that parallel wires carrying currents attract or repel each other. This was later known as electrodynamics. He invented the astatic needle and galvanometer as well.Modern Uses: The ampere the unit for measuring electric current was named in honor of Ampère. In the past, an ampere was understood as the force generated between parallel electrically charged wires, but as scientific knowledge evolves over time, the definition of “ampere” sometimes changesslightly also.

## The Aurora Borealis

Northern Lights are caused by the interaction of Earth's magnetic field with the flow of highly-charged particles from the Sun. Collisions of these particles with atmospheric molecules causes energy emission as visible light.

## Compass

the key mechanism behind a compass is the magnetic field generated by the Earths core. This field results in the North pole exhibiting a South magnetic polarity.

## Credit Cards

The strip on the back of your credit card is made up of magnetic particles that contain the account information. Any contact with a magnet or magnetic field can cause the strip to become demagnetized and the card to be ruined.

## Security Devices

A miniature disposable electronic circuit and antenna, attached to a product responds to a specific frequency emitted by a transmitter antenna.

## MRI

The largest part of the MRI is the primary magnet. Developing a magnetic field of adequate strength to create MRI images.

## Magnets on Refrigerator

A magnetic field is created as the result of moving charges. Basically the magnetic field of a magnet is created by the movement of electrons.

## VHS

Magnetic recording media VHS tapes contain a reel of magnetic tape. The information that makes up the video and sound is encoded on the magnetic coating on the tape.

## TV

Anytime the electrons move in the screens the is using electromagnetic force.

## Speakers

Electric current in the magnets and pulls on the diaphragm making this move resulting in sound waves being produced, these sound waves then enter your ear making you hear the noise. So the magnet helps produce the sound you hear from a speaker.

## Microphones

Mechanical element in them that vibrates sympathetically in response to the arriving acoustic wave fronts. This mechanical element acts on the electrical element to generate electromagnetic energy.

## Scrap Metal Crane

Electromagnetic crane has a huge electric magnet instead of a hook. This magnet is operated by an electrical current. When electric is switched on the magnet becomes magnetized, allowing metal objects to be picked up just like an ordinary magnets.