Fundamental concepts about electricity for learners



Electricity produced by friction between two dissimilar objects in known as static electricity. For example, if a glass rod is rubbed with silk, the rod requires positive charge and the silk an equal negative charge.

Conductors

Substances which have the ability to conduct electrical charges are called conductors. All metals conduct electricity because they have a large number of free electrons.

Insulators

Insulators have no free electrons and do not conduct electrical charges. Most non-metals are insulators. For example wood, glass, rubber, pure water.

Super conductors

The resistance of metal to flow of current reduces with decreasing temperature. At temperature near absolute zero which means -2730 C metals have almost zero resistance and became super conductor.

Certain ceramics can be made to behave as super conductors at relatively high temperature of above 100k.

Semi conductors

Certain materials have electrical resistivity intermediate between those of conductors and insulators. These materials are termed as semi conductors. For example, Silicon and Germanium are the semiconductor materials.

They are good insulators in their pure crystalline form but their conductivity increases small amount of impurities are added to them. After the addition of impurities, they become n-type and p-type semi conductors.

Lightning conductor

Lightning conductors are used to protect tall building from lightning damage. Here a thick copper strip is fixed to an outside wall of the building. The upper end of the strip is in the form of several sharp spikes reaching above the highest part of the building. The lower end is connected to a copper plate buried in the earth.

When clouds charged positively or negatively come near the spitted conductor, the clouds induce an opposite charge on them which is streamed off by the points.

In process, the clouds get discharged and an intense spark discharge, which might otherwise pass through the building causing heavy damage, is averted.

Magnetic effect of current

A current carrying wire has a magnetic field around it. Electromagnets are produced in this way. Strong electromagnets find lot of application in industry for lifting and transporting steel plates. They are used in electric bells, telephone receivers.

Heating effect of current

When a charge move in a conductor, it does work, which results in heating the conductor.

If the resistance of a wire is R ohms and the current flowing through it is I ampere, the heat produced per second in the wire is I2 R Joules.

The heating effect of current is used in geyser, electric iron, toaster, oven, room heater and so on. 


Some facts about electricity




Ic chips for computers are usually made of silicon.

Semiconductor is made of silicon and germanium.

Soft iron would be most suitable for making an electromagnet.

Nichrome wire is used as a heating element in many appliances. Because it has high resistivity and resist oxidation in air when red hot.

Energy conversions in a loudspeaker are electrical to mechanical to sound.

Energy conversion taking place in a microphone are sound to mechanical to electrical.
A transformer is a device for stepping up AC voltage.

The advantage of AC over DC is that it can be transmitted over long distances with minimum power loss.

The material used for a fuse wire should have low melting point.

One should not connect a number of electrical appliances to the same point socket. Because of this can damage the domestic wiring due to overheating.

Air is completely removed from an electric bulb to prevent oxidation of tungsten filament.

When an electric bulb breaks, there is a mild bang due to the air rushing in to fill the evacuated space.

A common fluorescent tube contains mercury vapor at low pressure.

Fundamental concepts about electricity for learners Fundamental concepts about electricity for learners Reviewed by knowledge people creators on April 07, 2020 Rating: 5
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