Kinds Of Charges: Attration And Repulsion Charge Distrubtion
When a glass rod is rubbed with silk,it gets charged and when an ebonite rod is rubbed with cat’s silk it also
gets charged.But the fllowing experiment shows that the charges of the two rods are of diffrernt type.If a
glass rod rubbed with silk is suspended by a thread and another glass rod rubbed with silk is suspended near
the first rod,then the two rods move away from each other.similarly, when an ebonite rod rubbed with cat’s skin
is suspended by a thread and another ebonite rod rubbed with cat’skin is suspended nesr the first rod ‘then the
two rods move towards each other.
The above experiment shows that the electric charge is of two types : One is that which is developed on the glass rod on rubbing it with silk and the other is that which is developed on the ebonite rod on rubbing with cat’s skin. The electric charge developed on glass rod is called positive charge and the charge developed on ebonite rod is called negative charge. These names were given by American scientist Banjamin Franklin (1706-1790) in 1750 A.D.
It is not necessary that glass rod 1s always electrified with positive charge and ebonite rod is alwayselectrified with negative charge. It depends upon the fact that against which other body these are rubbed. Forexample, when glass rod is rubbed against flannel it acquires negative charge.
In this way, the kind of charge developed on a body depends upon the nature of the body itself as also the nature of the body against which it is rubbed. Another observed fact about electric charge is that when it is produced by friction, i.e. , by rubbing twobodies with each other, both the bodies are electrified with unlike charges but of equal magnitude. For example, when glass rod is rubbed with silk the rod acquires positive charge while the silk acquires negativechargen of the same megntidue as that of positive charge on glass rod. When glass rod is rubbed with flannel, the rod acquires negative charge while the flannel acquires the positive charge of the same magnitude as that of negative charge on the glass rod.
Types Of charge Distrubtion
There are three types of charge distrubtion.
1: Linear Charge Distrubtion- When charge is distrubtion over whole length of conductor,then this distrubtion is called linear charge distrubtion. Charge per unit length of conductor is called linear charge density.It is generally denoted by “lemda”.If length of conductor is “L”and charge distrubted on it is”q”(Q).
2: Surface Charge Distrubtion- When charge is distrubted on whole surface area of body is “A”and charge distrubted over it is’Q’ ,then surface charge density is “row”.
3: Volume Charge Distrubtion- When charge is distrubtion it whole volume of conductor, then this distrubtion of charge is called voiume charge distrubtion.Charge per unit volume is called volume charge density.If volume of conductor is”v”and charge distrubtion in it is “Q”.