[Physics Class Notes] on Charging By Induction Pdf for Exam

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.

What is 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. This method of charging is the one in which with the help of a charged object, a neutral object is charged but without touching the objects. The charged particle is brought closer to a neutral or an uncharged conductor which is grounded on a material that is neutrally charged. If a charge flows between two objects, the uncharged conductive material will develop a charge whose polarity will be opposite to that of the charged object. 

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 by using a positively charged rod, involves the following procedure;

1. On two insulating platforms, place two metal spheres A and B, and bring them close.

2. A positively charged rod is brought close to A but don’t let it touch it. Free electrons in the rod are attracted by the sphere. A positive charge will accumulate on the rear surface of B. Both types of chargers are unable to escape the metal spheres. Because of this, the charges live on the surface of the metal spheres. A negative charge will accumulate on the left surface of sphere A while a positive charge will accumulate on the right surface of sphere B. All the electron particles are not collected on the left surface of A. The negative charge building upon A’s left surface repels all the other electron particles. The force of repulsion is caused by the accumulated charges under the operation of the attraction force of the rod due to which equilibrium is achieved in a shorter period.

3. Until the glass rod is held close to the sphere, the charges that are collected will remain visible on the surface. The charges will no longer be affected by the external forces when the rod is withdrawn and will revert to the original neutral condition.

In this process, the metal spheres will be equally and oppositely charged and the process is known as induction charging. In the whole operation, the positively charged rod will not lose any of its charges.

Charging by induction by using a negatively charged rod, involves the following procedure;

1. A and B are two metal spheres that are touching each other. A negatively charged rod is brought close to the spheres there will be repulsion between the electrons of the charged rods and the spheres cause the electrons to move away.

2. The electrons are transported from sphere A to sphere B due to which sphere A will become positively charged and sphere B will become negatively charged because of the migration of the electrons. 

3. The entire sphere system will become electrically neutral. When the charged rod is removed, the charge will redistribute through the spheres.

Electroscope

An electroscope is one of the common lab demonstrations that illustrate the charging by induction method. The devices that are used to detect the presence of an electric charge on an object are known as an electroscope. 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. The charges based on the Coulomb Electrostatic force which is responsible for the motion of the test charge are detected by an electroscope. It can also be regarded as a crude voltmeter since the electric charge is equal to the capacitance for an object. The instrument quantitatively measuring the charge is known as an electrometer.

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.

Conclusion

• 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.