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ELECTRIC WORLD

Tuesday, July 28, 2009

Dafinations

Insulator:-
Insulator are those materials that have very few free electrons and require a large applied voltage to establlish a measureable current level.
Semiconductor:-
Semiconductor are a specitic group of elements that exhibit characteristics that lie between those of insulators and conductors.semiconductor materials have four electrons in the outermost orbit.


Conductor:-
Conductors are those materials permit a generous flow of electrons with very little external force (voltage) applied.Good conductors have only one electron in valance ring.Resistance:-
The property of a substance which opposes the flow of electricity throught it is called resistance or resistance is the ability of a circuit to oppose current.
Conductance:-
Reciprocal of resistance is called conductance.
G=1/R OR R=1/G

Ohm,s law:-
In any electric circuit the current is directly proportional to the applied voltage and inversely proportional to the total circuit resistance.
I=V/R
V=IR
R=V/I

Temperature Co-efficient:-
Temperature co-efficient of resistance is the amount by which resistance changes when temperature changes when temperature change by one degree centigrat.

Resistors:-
A resistor is a component designed to have a known value of resistance or those components which are specially designed to have a certain amount of resistance are called resistors.

Work:-
If a force move a body throught a distance in the direction of application then work is done.
W=FS

power:-
Is the rate of doing work or power is the rate at which energy is used or power is the rate of converting energy.
P=W/T

Energy:-
Energy is capaacity for doing work or the ability to do work is called energy.

Magnetic field:-
Any space in which a magnetic effect can be detected constitutes a magnetic field.

Magnetic flux:-
The total number of lines threading throught the filed is called the magnetic flux.

Classification of magnetic materials:-
1:-Dia magnetic
2:-Paramagnetic
3:-Ferromagnetic

Dia magnetic materials:-
Materials made up of atoms having zero magnetic moment prove to be weakly repelled by a magnetic.They are called diamagnetic or non magnetic materials.

Paramagnetic materials:-
Tha materials have a permeabillity just slightly greater than that of space and are very slightly magnetised are called paramagnetic materials,e.g platinum alumlnum and oxygen etc.

Feromagnetic materials:-
The materials which can be magnetised very strongly are called ferromagnetic materials e.g iron cobalt or nickle.

Cycle:-
One complete set of positive and negative values of alternating quantity is known as caycle.

Period:-
The time taken by an alternating quantity to complete one cycle is called its time period.
T=1/F

Frequency:-
Frequency is the number of cycles passed thrpught per second.It is denoted by f and has the unit cycle per second.

Amplitude:-
The maximum value positive or negative of an alternating quantity is known as its amplitude.

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