Charging By Induction

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Charging By Induction Example

Most of the objects present in the universe are electrically neutral, that is they will be possessing equal numbers of charges. In order to charge the neutral bodies, we must create an imbalance of charges externally. Basically, there are three methods of charging an object charging by friction, charging by conduction, and charging by induction respectively. The neutral bodies are charged by friction when we rub the two bodies, charging by conduction can be done by touching a conducting body, and finally, the charging by induction is done by bringing two conducting bodies in contact or held near.

Charging a conducting body by induction method is most widely used, in this method we see that we can charge conducting bodies without even touching them. For understanding the charging by induction and charging by induction example one should have a thorough knowledge of the nature of conductors and polarization processes. In this article, we will have a deep insight into charging by induction method.


Charging By Induction Definition

The charging by induction definition states that it is a process of charging conducting bodies without touching them or by bringing the two conducting bodies near to each other. For example, let us assume that we have a neutral body such that there is no net charge i.e., the conducting body is having an equal number of positive and negative charges. Now we know conduction can be seen if we have mobile charges, due to the presence of an equal number of positive and negative charges it is considered to be a non-conducting body, this can be charged by bringing a negatively charged body near it and we will see all the positive charges get attracted and the charging by induction will be observed. Basically during charging by induction no charges will be flowing through the ground i.e., charging by induction grounding.


Charging By Induction Using a Negatively Charged System

One common Charging by induction example performed in physics is the charging of two metal spheres. The metal spheres are supported by the insulating stands so that any charge acquired by the spheres will not flow into the ground. The spheres are placed side by side of one another as shown in the figure below, such that it will form a two-sphere system.


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Now, the spheres are made of metal in particular a conductor, thus electrons are free to move between the spheres i.e., from sphere A to sphere B and vice versa. If a negatively charged rubber balloon (charged by rubbing, that created electrostatic field resulting in negative charges spread all over the surface of the balloon) is and brought near the conducting spheres, electrons within the two-sphere system will be induced to drift away from the balloon. 

This is simply the electrostatic principle that says unlike charges repel. Since the conducting spheres are charged negatively, the electrons are repelled by the negatively charged balloon. Due to the presence of electrons in a conductor, they are free to move about the surface of the conductor. Being charged negatively, the electrons are repelled by the negatively charged balloon. 

Now, there is a mass transition of electrons from sphere A to sphere B. This electron transition or the migration causes the two-sphere system to be polarized. Ultimately, the two-sphere system is electrically neutral. Yet the migration of electrons out of sphere A and into sphere B separates the charge from the charge. By watching the spheres individually, it might be appropriate to mention that sphere A has overall positive charges and sphere B has overall negative charges.

After the two-sphere system is polarized, sphere B is physically separated from sphere A using the insulating stand. Having been pulled beyond the balloon, the negative charges likely redistribute themselves uniformly about sphere B. At the same time, the excess positive charges on sphere A remain located near the negatively charged balloon, consistent with the electrostatic principle that opposite charges attract. 

As the balloon is moved away, there is a uniform distribution of charge about the surface of both spheres (As demonstrated in the figure). This distribution of charges occurs as the remaining electrons in sphere A transit across the surface of the sphere until the excess positive charge is uniformly distributed. 

Thus, when a negatively charged balloon is brought near the two-sphere system, the electrons in the sphere will be forced to move away due to repulsion. The migration of electrons will cause sphere A to become completely positive and sphere B to become negative.


Charging By Induction Using a Positively Charged System

Similarly, we study the transfer of charge through the method of induction employing a charged object. Consider two conducting spheres A and B, touching each other, if we bring a positively charged balloon near sphere A, the electrons from sphere B transit towards sphere A due to the attraction between opposite charges, thus leaving the sphere B electron deficient. As a result of this, sphere A is negatively charged and sphere B is positively charged. The conducting spheres are then separated using an insulating cover, a stand, or gloves. When the balloon is moved away, the charges in spheres A and B redistribute, spreading out evenly.

Thus, when a positively charged balloon is brought near the two-sphere system, the electrons from sphere B will migrate towards sphere A as a result of the force of attraction. Now, sphere A is negatively charged and sphere B is positively charged.


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Electroscope

An electroscope is one of the common lab demonstrations that illustrate the charging by induction method. So, in the Electroscope Lab, a positively charged object (for example objects such as an aluminium pie plate) is used to charge an electroscope by induction method. An electroscope is a device that is capable of detecting the presence of a charged object (irrespective of the polarity of charges). It is often used in electrostatic experiments and illustrations in order to test for charge and to deduce the type of charge present on an object. 

There are all types of varieties and brands of electroscope from the gold leaf electroscope to the needle electroscope designed as per the need. Though there are different types of electroscopes available, the basic operation of each electroscope is the same. Generally, the electroscope consists of a conducting plate or knob, a conducting base, and either a pair of conducting leaves or a conducting needle both work efficiently. Students can find more detailed explanations in charging by induction worksheet and try to solve charging by conduction and grounding worksheet answers.


Did You Know:

  • The charging by induction method is the most efficient method of charging and it is used in most applications. The charging by induction class 12 will help students to understand the importance of charging by induction.

  • In commercial products, the charging by induction process is governed with the help of induction coils. 

  • In smartphones, both the phone and therefore the charging dock contain induction coils of iron wrapped with copper wire. When we place the phone on the charging dock an electromagnetic field is produced between the induction coils. 

  • Once the electromagnetic field is produced, electricity is in position to pass between the two induction coils, charging the phone wirelessly.

FAQs (Frequently Asked Questions)

1. What is Charging By Induction?

Ans: Charging a conducting body by induction method is most widely used, in this method we see that we can charge conducting bodies without even touching them. The charging by induction definition states that it is a process of charging conducting bodies without touching them or by bringing the two conducting bodies near to each other.

2. What are the Three Methods of Charging?

Ans: Many objects that are present in the universe are electrically neutral, that is they will be possessing equal numbers of charges. In order to charge the neutral bodies, we must create an imbalance of charges externally. Basically, there are three methods of charging an object charging by friction, charging by conduction, and charging by induction respectively. The neutral bodies are charged by friction when we rub the two bodies, charging by conduction can be done by touching a conducting body, and finally the charging by induction is done by bringing two conducting bodies in contact or held near.

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