INSULATORS AND CONDUCTORS

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 Insulators
In the process of charging by friction we find that one category of materials can be easily charged. Such materials include glass,
ebonite, hard rubber and fur. In this category, the electrons transferred from one material to another remains on the surface of the material. They do not move about within the material, but are confined or localized at the point of rubbing, such materials are known as electrical insulators. All electrons in electrical insulators such as polythene, cellulose acetate, perspex, ebonite and glass sre firmly bound to their nuclei. The removal or addition of electrons in one region does not cause electrons to flow. The charge is confined or localized to the point where it was produced or placed.

Conductors
There is another category of materials such as metals through which electrons flow. In this category, materials are not easily electrified by rubbing with silk or fur unless they are well insulated first. Such materials are known as electrical conductors. In electrical conductors such as metals, the outer or valence electrons are loosely bound to their nuclei. Hence, these valence electrons are de localized and can move about freely within the conducting materials. If such a material gains electrons, the electrons can also move about in them.

Similarly the loss of electrons by a conductor causes a redistribution of those electrons left behind, resulting in the movement of electrons as well. Other electrical conductors includes electrolytes which are liquids and ionized gases which contain positive and negative ions that are free to move about.

Semi conductors
There is a third category of materials whose electrical property are between those of conductors and insulators. They have fewer free electrons that conductors. Such materials are known as semi conductors. Examples of semiconductors include silicon and germanium.

To neutralize a charged body is to remove the excess positive or negative charge from it, this process is known as discharging.

Charged insulators
Just as it requires effort to charge an insulator such as a glass rod by rubbing it with silk, effort is also needed to remove the excess charge from it. This is due to the fact that the excess charges on the insulator do not move easily. One way to quickly discharge a charged insulator like a glass rod is to heat it over a flame. The intense heat causes the air surrounding the glass rod to become quickly ionized into positive and negative ions. These negative ions neutralize the excess positive charges on the glass rod. Likewise for a negatively charged ebonite rod, positive ions in the heated air will neutralize the negative excess charges on the ebonite rod. All charged insulators also discharge slowly when left in humid conditions. The water vapor in the air causes the excess charges on the insulator to leak away slowly.

Charged conductors
For a charged conductor such as a metal sphere with excess electrons, the electrons can be removed by earthing it. To earth a charged conductor is to provide a path for the electrons to flow away from or towards the charged conductor, causing it to become electrically neutral. This is very important in your quest to pass your WAEC and JAMB exams. The term earth when used as a noun refers to any large conductor from which electrons may be taken or to which electrons may be given without the conductor itself becoming noticeably charged. Share.