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Charging:
Charging of an object is possible in 3 ways:
By Friction
By conduction
By induction.
Here, in this article, we will be discussing charging by friction in detail. But before that, you must be aware of the fact that when a body loses electrons it becomes +vely charged and when a body gains electrons it becomes negatively charged. One of the most important points to be kept in mind, only non-conducting materials/objects or insulators can be charged by friction, because in conducting materials the particles are free to move but in insulators, charges are not free to move so you have to rub them to make the charges move from one place to the other.
Friction:
Before we get into Charging by friction, let us discuss what is friction? Friction is a force that is generated between two surfaces when they are in contact and there is a slight or more motion between the surfaces.
Technically, friction is a force that resists the relative motion between two objects.
Charging by friction can be done by generating an imbalance of electrons and protons between two bodies and this imbalance can be easily made by rubbing the two bodies.
What is meant by rubbing? It is nothing but moving two bodies back and forth by keeping close contact between them.
The most common example of charging by friction is rubbing an ebonite rod with a fur, here the fur loses electrons and becomes positively charged whereas the ebonite rod gains electrons and becomes negatively charged.
Effects on Charging by Friction on an object
When an object is made to rub with another object an imbalance of subatomic particles takes place between those two objects. As we know that electrons are free to move but protons are not. So,due to this imbalance the negatively charged particles move from one object to another and the object that gains electrons becomes -vely charged. This rubbing of electrons generates static electricity which is also called frictional electricity.
Charges are quantized:
The quantization of charge refers to the fact that the transferred electrons are the integral multiples of the basic charge e i.e it can only be increased or decreased in multiples of e.
Here , ‘e’ refers to unit of charge.
Numerically ‘e’ is equal to 1.6 x 10-19 C.
From this we can conclude that charges less than 1.6 x 10-19 C can not exist in nature. So when charges are generated with friction they are always the multiples of ‘e’ .
Examples of Charging by Friction:
As discussed earlier, rubbing an ebonite rod with fur is one of the widely used examples of charging by friction.
Rubbing a comb through dry hair generates negatively charged particles in the comb, this is the reason why small bits of paper are attracted towards the comb when brought nearby.
Rubbing silk cloth with hard rubber.
These are a few examples that you can come across in your daily life.
Materials charged by Friction
Which materials are charged by friction ? Not all materials are by friction. Only the non-conducting or insulating materials are changed by friction. The reason to this is because the particles are not free to move in case of insulators so to move them from one object to another or to bring them to the surface we have to rub them. Eg: hair and comb, ebonite rod and fur etc.
Triboelectric Series:
Materials have various atomic particles within them, which makes particles have different properties, one such property is electron affinity. Electron affinity is the is property which shows the electron holding property of a material. Different materials have different affinities for electrons. So on the basis of this few materials have been arranged in decreasing order or their charging by friction.
Asbestos > Glass > Wool > Fur > Lead > paraffin wax > ebonite > rubber > metals.
The following materials arranged above in a series are called the Triboelectric series.
Conclusion
From this article, we get the basic knowledge of how and why charges are generated with friction or by rubbing, what materials can be charged using friction, what are the examples of charging by friction that you see in your daily life.
