Everything is made up of tiny particles called atoms. The atoms are made up of even smaller parts called protons, electrons and neutrons. Protons have a positive charge (+), electrons have a negative charge (-) and neutrons have no charge at all, they are neutral. Atoms normally have the same amount of electrons and protons, making them neutral and having no charge. When rubbing things together, electrons can move from one atom to another, resulting in some atoms having extra electrons and a negative charge. The other atoms now have more protons than electrons and a positive charge. When the charges are separated, it is static electricity.
“Electricity is present in all matter in the form of electrons and protons. Any device that develops and maintains a voltage can be considered a voltage source. To accomplish this, the voltage source must remove electrons from one point and transfer electrons to a second point.” (Petruzella, 2001.) One type of electricity is static electricity. The term static means standing still which makes static electricity an electric charge that is at rest. Static electricity is defined as “an accumulation of electric charge on an insulated body.” (Free Dictionary) In other words, it is a charge that is created when two objects that are not good electrical conductors are rubbed together, and electrons from one of the object rub off onto the other object. Some of the results of static electricity may be sparks, shocks, or even materials clinging together.
The simplest way to form static electricity is by friction. Friction is simply the rubbing of one object against another. By rubbing two different materials together, “electrons may be forced out of their valence shells in one material and picked up in the shell of the other material. The material that gives up electrons more freely becomes positively charged and the one that gains electrons becomes negatively charged.” (Petruzella, 2001.) When the electrons are relocated from one material to another, it is called triboelectric charging.
Static electricity is formed much better in areas with low humidity and dry air. With humid air, tiny water molecules can collect on the surface of different materials and prevent the buildup of an electrical charge. Although small amounts of water, such as those developed from humidity, can affect a charge, “extreme turbulence among water drops”, such as in a thunderstorm cloud, can cause static electricity to build up on the water droplets themselves. Benjamin Franklin showed that static electricity is created in a thunderstorm cloud by flying a kite during a storm. He noticed the static electricity by seeing the hairs on the kite stand on end and created an electric spark with a metal key.
There are other ways to produce a static charge other than friction or contact. An object can also be charged by induction. Induction is used to produce a charge of opposite polarity. Inductance is defined in the text as an “electrical property which opposes change in current.” (Petruzella, 2001.) An inductor is “a device that generates a counter emf that tends to oppose any change in current through the use of ac current flowing through a coil wire.” (Petruzella, 2001.) Charging by induction makes use of the electrostatic field surrounding a charged body in order to charge an object without touching it. If a negatively charged rod is brought close to the sphere on the inductor, the negative charges in the sphere move as far away from the rod as possible. By touching the sphere, it is grounded and allows the electrons to completely leave the sphere. Once you remove your finger, the electrons no longer have a way of returning to the sphere and the rod is then positively charged.
Static electrical charge can be produced by a high-voltage direct current source. Many air purifiers use both positively and negatively charged plates to remove tiny dirt particles from the air. This system...
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