# Charge Transfer and Its Methods, About Charge Transfer Complex (For CBSE, ICSE, IAS, NET, NRA 2022)

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# Charge Transfer and Its Methods

A charge transfer complex also called as the electron donor acceptor complex can be defined as an association of two or more molecules, or of different parts of a large molecule, in which a fraction of electronic charge is transferred between the molecular entities.

### Structure of One Part of One Stack of the Charge-Transfer Complex between Pyrene

• We all have observed that when we charge a piece of plastic, a comb or a pen and position it near small pieces of paper they get attracted towards it.
• Also; the comb loses its charge after a few moments. One can say the charge gets transferred to our hand and eventually to the ground. But how does this phenomenon occur?

## Methods of Charge Transfer

There are two methods through which charge transfer can take place between two bodies.

• Charge transfer by Conduction
• Charge transfer by Induction

## Charge Transfer by Conduction

• Charging by conduction involves the contact of a charged object to a neutral object.
• So, when an uncharged conductor is brought in contact with a charged conductor, charge is shared between the two conductors and hence the uncharged conductor gets charged.
• During charging by conduction, both objects acquire the same type of charge.
• The charge transfer by conduction process involves touching of a charged particle to a conductive material.
• This way the charges are transferred from the charged material to the conductor. This method is useful for charging conductors.

### Charge Transfer by Conduction Using a Negatively Charged Object

• To explain the process of charging by contact, first consider the case of using a negatively charged metal sphere to charge a neutral needle electroscope.
• Understanding the process demands that you understand that like charges repel and have an intense desire to reduce their repulsions by spreading about as far as possible.

### Charging of a Neutral Object by Conduction

• A negatively charged metal sphere has an excess of electrons; those electrons find each other repulsive and distance themselves from each other as far as possible.
• The perimeter the sphere is the extreme to which they can go.
• If there was ever a conducting pathway to a more spacious piece of real estate, one could be sure that the electrons would be on that pathway to the greener grass beyond.
• So, electrons living in the same home despise each other and are always seeking a home of their own or at least a home with more rooms.
• Given this electron-electron repulsion, it is not difficult to predict what excess electrons on the metal sphere would be inclined to do if the sphere were touched to the neutral electroscope.
• Once the contact of the sphere to the electroscope is made, many numbers of excess electrons from the sphere move onto the electroscope and spread about the sphere-electroscope system.
• The object that offers the most space in which to “hang out” will be the object that houses the greatest number of excess electrons.
• When the charging process by conduction is complete, the electroscope acquires an excess negative charge due to the movement of electrons onto it from the metal sphere.
• The metal sphere is still charged negatively, only it has less excess negative charge than it had prior to the conduction charging process.

### Charge Transfer by Conduction Using a Positively Charged Object

• The diagram shown below depicts the use of a positively charged aluminum plate being touched to a neutral metal sphere.
• A positively charged aluminum plate has an excess of protons.
• When looked at from an electron perspective, a positively charged aluminum plate has a shortage of electrons. So, we could say that each excess proton is rather discontented.
• It՚s not satisfied until it has found a negatively charged electron with which to co-habitat.
• Though, a proton is tightly bound in the nucleus of an atom, it is incapable of leaving an atom in search of that longed-for electron.
• It can attract a mobile electron towards itself and if a conducting pathway is made between a collection of electrons and an excess proton, one can be certain that there is likely an electron that would be willing to take the pathway.
• When the positively charged aluminum, plate is touched to the neutral metal sphere, countless electrons on the metal sphere migrate towards the aluminum plate.
• There is a mass migration of electrons until the positive charge on the aluminum plate-metal sphere system becomes redistributed.
• Having lost electrons to the positively charged aluminum plate, there is a shortage of electrons on the sphere and an overall positive charge.
• The aluminum plate is still charged positively; only it now has less excess positive charge than it had before the charging process began.

### Charge Transfer by Conduction Using a Positively Charged Object

In the above example, we learnt about charge transfer through the process of conduction using a positive or a negatively charged object. Charge transfer can also take place through the process of induction.

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