Introduction to Static Charge

Key Concepts

• Charging an object by rubbing
• Static Electricity
• Electrostatic Series

Introduction:

Pieces of paper are attracted to a comb only after the comb has been rubbed; a balloon is attracted to the wall only after rubbing; if you wait for a while, the attractive property of the comb and the balloon disappear. This attractive or repulsive property acquired on rubbing is called static electricity, and an object that exhibits electric interaction after rubbing is said to be charged. 

Explanation: 

An atom is made up of positively charged protons, uncharged neutrons, and negatively charged electrons. 

The protons and neutrons exist inside the nucleus. The electrons are located outside the nucleus and move around it in orbits. 

Protons and neutrons are relatively fixed in the nucleus of the atom, but electrons are mobile and can be transferred from one atom to another. 

Neutral Atom: 

The nucleus is made of protons and neutrons. 

Electrons exist outside the nucleus in orbits. 

In a neutral atom: No. of protons = no. of electrons 

Position Ion: 

In a positive ion: No. of protons > no. of electrons 

Negative Ion: 

In a negative ion: No. of protons < no. of electrons 

When two materials touch one another, electrons can move from one material to the other. This causes one material to become more negatively charged than the other.  

Activity: 

Rub a wool cloth with a balloon. The woolen cloth tends to lose electrons more easily than the atoms in the balloon. Thus, on rubbing, the balloon gains a net negative charge, and the woolen cloth would have a net positive charge. 

Observation: 

The material (balloon) that gains electrons become negatively charged because it has more electrons.  

The material (Woollen sweater) that loses electrons becomes positively charged because it loses electrons. 

Conclusion: 

The transfer of electrons from one place to another causes an imbalance of positive and negative charges. This results in static electricity.  

Electrostatic Series: 

We arrange the materials in a chart called electrostatic series. 

• The material closer to the top has a tendency to lose electrons easily on rubbing, so it will have a positive charge on rubbing. Static electricity is the build-up of positive or negative electric charges on a material’s surface. 
• The material closer to the bottom has a tendency to hold electrons tightly or gain electrons, so it will have a negative charge on rubbing. 
• The material in the middle of the electrostatic series neither loses nor gains electrons, so it will have a neutral or no charge on rubbing. 

Example: Combing hair with a plastic comb  

Hair is higher on the electrostatic series than plastic. Therefore, it will give up some of its electrons to the comb and become positively charged. The comb will become negatively charged. 

The objects with opposite charges attract each other, and sometimes, these kinds of materials stick together. This is called a static cling. 

Objects get charged on rubbing, and when they are brought close to each other, they attract or repel, but all these experiments work best on a dry day because excessive moisture can provide a pathway for the charge to leak off from a charged object.

Summary

• The attractive or repulsive property acquired on rubbing is called static electricity and an object that exhibits electric interaction after rubbing is said to be charged.
• An atom is made up of positively charged protons, uncharged neutrons, and negatively charged electrons.
• The protons and neutrons exist inside the nucleus. The electrons are located outside the nucleus and move around it in orbits
• • Protons and neutrons are relatively fixed in the nucleus of the atom, but electrons are mobile and can be transferred from one atom to another.
• Protons and neutrons are relatively fixed in the nucleus of the atom, but electrons are mobile and can be transferred from one atom to another.
• We arrange the materials in a chart called an Electrostatic series
• The material closer to the top have a tendency to lose electrons easily on rubbing so it will have a positive charge on rubbing.
• The material closer to the bottom have a tendency to hold electrons tightly or gain electrons so it will have a negative charge on rubbing.
• When two materials touch one another, electrons can move from one material to the other.This causes one material to become more negatively charged than the other.
• Objects get charged on rubbing and when they are brought close to each other we see that:
• The objects with the same electric charge repel each other.
• The objects with opposite charges attract each other and sometimes these kinds of materials stick together. This is called a static cling.