Magnetic field around a bar magnet
The spinning of the electrons around the nucleus of an atom creates a tiny magnetic field. The electrons in most objects spin in random directions, and their magnetic forces cancel each other out.
Magnets are different because the molecules in magnets are arranged so that their electrons spin in the same direction. This arrangement and movement creates a magnetic force that flows out from a north-seeking pole and from a south-seeking pole. This magnetic force creates a magnetic field around a magnet.
Have you ever held two magnets close to each other? They don't act like most objects. If you try to push the two north poles or two south poles together, they repel each other. But if you put a north pole and a south pole together, the magnets will stick together because the north and south poles attract each other. Just like protons and electrons—opposites attract in magnets.
Magnetic fields can be used to make electricity
The properties of magnets are used to make electricity. Moving magnetic fields pull and push electrons. Metals such as copper and aluminum have electrons that are loosely held. Moving a magnet around a coil of wire, or moving a coil of wire around a magnet, pushes the electrons in the wire and creates an electrical current. Electricity generators essentially convert kinetic energy (the energy of motion) into electrical energy.
Last updated: October 26, 2017
The Electric Generator Essay
NOTE: This paper explains the theory and uses of the electric generator, and explains the differences between AC and DC generators. It also includes a glossary and a bibliography.
In its most basic definition, an electric generator is a machine that produces electricity. Generators produce almost all of the electricity used by people. They supply the electric power that runs machines in factories, provide lighting, and operate appliances in the home. There are two main types of generators - alternating-current (AC) generators (sometimes called alternators) and direct-current (DC) generators (also known as dynamos). Both types of generator work on the same principles.
How A Generator Works (Basic Principles)
A generator does not create energy - "energy cannot be created or destroyed, only changed from one form to another" (Sir Isaac Newton). A generator changes mechanical energy into electric energy. Every generator must be driven by a machine that produces mechanic energy. For example, the large generators that provide electricity to Lae and the rest of PNG are driven by hydro power. The mechanical device that powers a generator is known as a prime mover. To obtain more electrical energy from a generator, the prime mover must supply more mechanical energy.
Generators produce electricity by means of a principle discovered independently by two physicists in 1831 - Michael Faraday of England and Joseph Henry of the United States. Faraday and Henry found that they could produce electricity in a coil of copper wire by moving the coil near a magnet. This process is called electromagnetic induction.
A simple generator (see Figure 1 below) consists of a single loop of wire turning in a magnetic field. Electricity is produced only while the loop is rotating. As the loop rotates, the two sides "cut" the magnetic lines of force. This induces electricity into the loop. One complete revolution of the loop through the lines of force is called a cycle. The frequency of the voltage or current, which is number of cycles in a second, is measured in units called hertz (one hertz equals one cycle per second). The rotating loop is connected to an outside circuit by either a pair of slip rings (in an AC generator) or a commutator (in a DC generator). These connections are the only mechanical differences between AC and DC generators.
Alternating Current (AC) Generators
The simple generator shown in Figure 1 produces alternating current, in which the electricity flows regularly in one direction and then the other, in a loop of wire. Slip rings and brushes on each end of the loop of wire allow the generator to send the current produced to the devices that use...
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