Charging by Induction

Charging by induction is to charge an object without touching the object with any other charged object. This is related to polarization, which is the process of separating opposite charges inside an object.

  

One of the ways to try charging by induction is to use two metal spheres in an experiment. The metal spheres are held up by insulated stands, so charges cannot move between the ground and the spheres. The spheres and the stands are put side by side, so electrons can move freely between the metal spheres. When a negatively charged balloon is placed near the two negatively charged spheres, the negative charges will start to move in the spheres, because similar charges repel. The electrons start to freely move around the surface of the conductor, and the charges move from one sphere to the other. This is an example of polarization. The polarization leaves the metal spheres neutral, but the electrons moving from the spheres separates the positive sphere and the negative sphere.

The induction experiment can also be used with soda cans and styrofoam cups. The cans are taped on the cups, and are placed side by side. A negatively charged balloon is brought near one of the cans. The negative charge near the can repels the electrons to the other can, once the cans are separated, the cans are charged. 

Charging by Friction

Friction is the force resisiting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. 

There are a few types of friction:

·    Dry Friction: resists relative motion of two solid surfaces in contact. Dry friction has to categories:

1. Static friction between non-moving surfaces 2. Kinetic friction between moving surfaces.

·    Lubricated friction: fluid friction where fluids seperate 2 solids.

·    Skin friction: a component of drag, forces resisting motion of a solid body through fluids.

·    Internal friction: forces resisting motion between elements making solid materials while undergoing deformation.

When surfaces that are touching move relative to each other, the friction between the two surfaces kinetic energy into heat. Such as when wood is rubbed together, the friction causes a fire because  the kinetic energy transforms into heat. Friction has consquences such as being burned by the fire or objects having performance degradations. Friction comes from electromagnetic forces from two or more charged objects.

Grounding - Removal of a Charge

To remove the electric charge from any object, the electrons of the object must be removed. There are several ways to remove an electric charge from an object. One of the ways to remove the charge is by grounding. Grounding is basically removing electrons from an object by transferring the electrons into another object.

An example of removing a charge using the grounding method is by using an electroscope. The objective is to neutralize the charges from the electroscope by removing the electrons. After removing the electrons, the number of protons and electrons will be the same, so the charge will be neutral. The process of removing the electrons is by connecting an object to another object that will receive the electrons. If the electroscope is positively charged, the process will be similar. To neutralize a positively charged electroscope, we must add electrons to balance the charges. The electrons are gained from the ground, and the process works because the positively charged electroscope will attract the electrons from the ground.

Recommended: http://www.physicsclassroom.com/class/estatics/u8l2d.cfm

Charging by Conduction

General

Charging by conduction, or also known as charging by contact, is the transfer of electrons from a charged object to a neutral object that requires a physical connection. There can be two cases of charging by conduction, that is to either use a negatively charged object or a positively charged object.

Charging by Conduction – Negatively Charged Object

When a neutral object meets a negatively charged object, it will become negatively charged as well. To make sense of this, we must understand that a negatively charged object has an excess amount of electrons. Electrons need their own space, and so repel from one another. The electrons in a neutral object is not packed together, so when a neutral object comes in contact with a negatively charged object, a bridge is formed and allows the excess of electrons to run towards the open space. When the electrons move, the negatively charged object stays negative, and the neutral object gains more electrons, hence charging it negatively.

Charging by Conduction – Positively Charged Object

In a positively charged object, the number of protons is excessive. Unlike electrons, protons are attached to the neutrons, thus cannot move around as easily. When a positively charged object comes in contact with a neutral object, it will attract the electrons. To understand why the electrons would leave its comfortable conditions in the neutral object, we must know that electrons and protons’ purpose is to help balance the ones in need. When the positively charged object rubs off the neutral one, the electrons in the neutral one notice the excessive amount of protons and move to it. The positively charged object stays positive with less excessive protons, and the amount of electrons in the neutral object reduces, ergo it becomes a positively charged object.

Resource: http://www.physicsclassroom.com/class/estatics/u8l2c.cfm

For an animation, click below:
Conduction - Negative and Positive