Demonstration of Electrostatic Simulation

Theoretical Background / Context

• Electric charge is one of the fundamental properties of matter. Electrostatics is the study of electric charges and their characteristics. 
• For example, like charges repel and unlike charges attract. An object is often electrically neutral; that is, it has a balance of positive and negative electric charges. 
• Rubbing different materials together, contact with a charged object, and charging by induction are three ways to create an imbalance of electric charge – sometimes called static electricity. 
• Some charge-detecting or measuring device is needed to experimentally investigate electrostatics. 
• A common instrument for this purpose is the Electrometer, a voltmeter used for direct and indirect measurements of voltage and current and charge. 
• The charges can transfer from one object to another, this process is called Charging. 
• For an object to become positively charged, it must lose some of its electrons. 
• For an object to become negatively charged, it must acquire more electrons.

Principle of Work

In the electrostatic simulation experiment we will study different methods of charging and charge distribution on conductors.

Charging:

• The charges can transfer form one object to another, this process called Charging. 
• In order for an object to become positively charged, it must lose some of its electrons. 
• In order for an object to become negatively charged, it must acquire more electrons. 

The Different Way for Charging Can Be Summarized As:

1- Charging by rubbing: 

• When two initially neutral non-conducting objects are rubbed together, one of them will generally bind electrons more strongly than the other and take electrons from the other. 
• The law of conservation of charge requires that the total amount of electrons be conserved. 
• That is, electrons only move from one object to another, but no new electrons are created, nor do they disappear. 

2- Charging by contact: 

• When a charged object is touched to a neutral (or less charged) object, repulsive forces between the like charges result in some of the charge transferring to the less charged object so the like charges will be further apart.  
• This effect is much larger for conducting objects.

3- Charging by induction:  

• The protons and electrons inside any object respond to electric forces of attraction or repulsion. 
• When an object is placed near a charged object, the charged object will exert opposite forces on the protons and the electrons inside the other object, forcing them to move apart from each other. 
• One side of the object will become more positive than it was initially.  
• The other side will become more negative, as electrons migrate internally. This condition is called polarization, and it is a fundamental demonstration of polarization in electrostatics.

Figure 1: Experiment setup for study charging

Charge Distribution

1- Charge Distribution on a Conducting Surface: charge will tend to concentrate at places on a conductor where the surface is more sharply curved. This happens because charges do not interact as strongly with other charges that are “over the horizon” since the electric field lines cannot pass through a conductor.

2- Charge inside a Spherical Conducting Shell: if the force between two point charges obeys an inverse square law (i.e. falls off like 1/r2), then all the charge on a conducting spherical shell must lie on the outside of the shell and the inside of the shell must be uncharged.

Figure 2: Experiment setup for study charge distributio