Charging by Induction

Introduction 

Every solid object is made up of tightly packed atoms. The force of attraction between the electrons and protons is so high that free charges are absent in solids. However, under influence, the electrons can accumulate at the surface of the material. Such a phenomenon leads to the formation of a charged body. 

This is the preliminary method of transforming a non-conductive body into a charged one. It is not similar to that of the electricity conducting wires. But when measured, a certain amount of coulomb reading will be there, proving that static charges have accumulated near the surface.

What is static charge?

Let’s consider a rubber ball. Being a solid structure, it has tightly packed atoms with a high force of electrostatic attraction between them. As it’s a neutral body, the number of protons and electrons are the same. If there are x number of positive charges, x number of negative charges should be there to balance the electrostatic nature. 

However, sometimes, under the influence of friction or any charged body, the electrons get enough energy to overcome the electrostatic force of attraction. Therefore, the outermost electrons revolving around the nuclei become free. They move towards the surface, due to which a polarity develops. 

Such charges don’t move from their places or form a “drift” which is why they are termed as static charges. Here, a single static charge will be represented by the letter ‘q’ for better understanding. 

How does static charge form?

To learn more about charging by induction, it is important to understand how static charges are formed. Let’s consider two bodies- a charged body A and an electrostatically neutral body B. Body A can have two types of static charges:

1. If there are many holes or vacant spaces in the atomic lattice of the object, we will call it a positively charged body. 
2. In case body A has excess electrons freely roaming in the crystal lattice, we will call it a negatively charged body. 

When body A is brought closer to body B, charging by conduction and induction is possible. There will be a transfer of charges from A to B depending on the type of electrostatic charge in body A. 

About charging by induction

Charging by induction is a process by which a neutral body can be charged electrostatically in the presence of a negatively or positively charged body. The induction process means there won’t be any physical contact between these two bodies.  

How does charging by induction take place?

Charging by induction takes place while following the law of conservation of charge. In terms of physical science, in electromagnetic induction the induced charge is independent of the body mass, size, and other such properties. It is strictly based on the law that states:

“The total quantity of charge in an isolated system will never change and always remain at a constant value. Even if there is an exchange of charges between two bodies in the system, the number of positive charges will be equal to the negative charges to make the entire system electrostatically neutral.”

When charging by induction takes place in the presence of a charged body, electrostatic force of attraction comes into play. Like charges will always repel each other while the unlike charges will be attracted. Based on this phenomenon, the neutral bodies in the isolated system become positively and negatively charged. 

To understand the process, let’s learn a little about charging by induction, an example that happens in our daily lives. After combing dry hairs, the comb’s surface will have electron accumulation. When this comb is brought closer to pieces of paper, they get attracted because of the electrostatic force of attraction. 

Another charging by induction process that can be performed is by using a fur fabric. Take a rubber balloon being rubbed with silk. It will have negatively charged particles or electrons accumulating close to the surface. 

When this rubber balloon is brought closer to a glass rod, the nearest end will become positively charged, and the farthest end will become negatively charged. This is because the negatively charged electrons in the rubber balloon will repel the electrons in the glass road, thereby pushing them to the farthest end. 

What are the ways of charging an object with induction?

Charging by induction is basically done in two ways which will be described below for a better understanding of the process. 

Induction charging with a negatively charged body

1. An isolated system of two neutral spheres, A and B, is taken where they are kept on insulated stands for safety. 
2. A negatively charged body C is brought closer to sphere A maintaining a minimum distance between them. 
3. No physical contact takes place between A and C.
4. Since C has more electrons on its surface, it will repel the electrons present in sphere A. 
5. As a result, the negative charges will move towards sphere B and accumulate at the farthest point. 
6. As electrons will move further to sphere B, vacancies or holes will be created in sphere A. Hence, it will become positive.

Once charges move apart from each other, the spheres can be removed with the help of insulated stands. Therefore, sphere A will have positive charges while sphere B will have negative charges. After separation, the charges will get distributed evenly on the surface.

Induction charging with a positively charged body

1. In an isolated system, two neutral spheres have been taken. A positively charged body is brought near sphere A. 
2. The positive charges will attract negative charges or the unlike charges towards the nearest surface in sphere A. 
3. As a result, sphere A will become negatively charged. 
4. A vacancy or collection of holes will be created in sphere B, which will make it positively charged. 
5. After separating the two bodies, the charges will get distributed. Sphere A will have negative charges while sphere B will have positive charges. 

What is the difference between charging by induction and conduction?

Charging by conduction and induction are almost similar, with the only difference being in the way charges are transferred. In conduction, there is a physical contact between the charged and neutral body. In contrast, in electromagnetic induction the induced charge is independent of any type of contact. 

Conclusion 

Charging by induction example can be seen in real life only. Static charge build-up in appliances, the attraction of the paper bits to a comb, and so on are natural phenomena that can be explained by the process of electromagnetic induction. Additionally, this process makes sure that the neutral bodies can remain charged up for more time compared to other methods. No matter what the charge type is or the quantity of charge build-up, the total number will remain the same because no new charge is created. Rather, the electrons and protons simply change their positions following one of the main principles of electrostatics.