Transcript Electricity
Electricity From then til Now…. Noteworthy Scientists and Inventors • 1729 The English physicist Stephen Gray discovered electrical conductivity in 1729. • 1752 Benjamin Franklin proposes the notion of positive and negative charge, conserving a balance except when a deficit is brought about by some means. • 1800 Alessandro Volta invents an electric battery, the first source of DC current. Noteworthy Scientists and Inventors • In 1827, using equipment of his own creation, Georg Simon Ohm determined that the current that flows through a wire is proportional to its cross sectional area and inversely proportional to its length or Ohm's law. These fundamental relationships are of such great importance, that they represent the true beginning of electrical circuit analysis • 1879 Thomas Alva Edison invented the light bulb, and houses, shops, factories, schools, streets, ballparks -- every place you could think of, indoors and out -- could at last be easily illuminated after dark. Noteworthy Scientists and Inventors • Nikola Tesla Referred to as the greatest inventive genius of all time. Tesla's system triumphed to make possible the first large-scale harnessing of Niagara Falls with the first hydroelectric plant in the United States in 1886. • On March 20, 1886, William Stanley demonstrated a system of high voltage transmission via a "parallel connected transformer." The device, combined with high-voltage transmission lines, made it possible to spread electric service over a wide AreA • October 1893 George Westinghouse (1846-1914) was awarded the contract to build the first generators at Niagara Falls. He used his money to buy up patents in the electric field. One of the inventions he bought was the transformer from William Stanley. • Otto Hahn (1879-1968), a German chemist and physicist, made the vital discovery which led to the first nuclear reactor. He uncovered the process of nuclear fission by which nuclei of atoms of heavy elements can break into smaller nuclei, in the process releasing large quantities of energy. • 1901 Elihu Thomson, electrical engineer, inventor, and entrepreneur, was an innovator in electrification in both a technical and corporate sense. Thomson acquired nearly 700 patents in his career, his major contributions included (electrostatic motors, electrical meters, high-pressure steam engines, dynamos, generators and, X-rays). It all started with a bolt… • Electricity (from the New Latin, "amber-like”, from the Greek (electron) meaning amber) • is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. • These include many easily recognizable phenomena, such as lightning and static electricity, but in addition, less familiar concepts, such as the electromagnetic field and electromagnetic induction. • Electric charge: a property of some subatomic particles, which determines their electromagnetic interactions. Electrically charged matter is influenced by, and produces, electromagnetic fields. •Electric current: a movement or flow of electrically charged particles, typically measured in amperes (amps). •Electric field: an influence produced by an electric charge on other charges in its vicinity. •Electric potential: the capacity of an electric field to do work on an electric charge, typically measured in volts. •Electromagnetism: a fundamental interaction between the magnetic field and the presence and motion of an electric charge. Types of Electricity • There are two types of ElectricityStatic Electricity and Current Electricity. Static Electricity is made by rubbing together two or more objects and making friction, while Current electricity is the flow of electric charge across an electrical field. Static Electricity • Static electricity is when electrical charges build up on the surface of a material. It is usually caused by rubbing materials together. The result of a build-up of static electricity is that objects may be attracted to each other or may even cause a spark to jump from one to the other. Current Electricity • Current is the rate of flow of electrons. It is produced by moving electrons and it is measured in amperes. Unlike static electricity, current electricity must flow through a conductor, usually copper wire. With electricity, current is a measure of the amount of energy transferred over a period of time. That energy is called a flow of electrons. One of the results of current is the heating of the conductor. When an electric stove heats up, it's because of the flow of current. Two Kinds of Electric Current • There are two main kinds of electric current. Direct (DC) and Alternating (AC). • Direct current is like the energy you get from a battery. • Alternating current is like the plugs in the wall. • The big difference between the two is that DC is a flow of energy while AC can turn on and off. AC reverses the direction of the electrons.