Electric Charges

Key Concepts

• Charging an object by rubbing
• Static electricity
• Cause of charging

Introduction: Electric Charges

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: 

When we rub the cat’s fur with a comb, we see that the atoms in a cat’s fur tend to lose electrons more easily than the atoms in the comb. If we comb the cat’s fur, the comb gains a net negative charge and the cat’s fur would have a net positive charge. 

The material (comb) that gains electrons becomes negatively charged because it has more electrons.  

The material (cat’s fur) that loses electrons becomes positively charged because it loses electrons. 

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. 

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:

• Pieces of paper are attached wall only after rubbing, if we 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.
• 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.
• In a neutral atom: No. of Protons = No. of electrons
• In a positive ion: No. of Protons > No. of electrons
• 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.
• 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.

Frequently Asked Questions (FAQ’s): 

1. What is an electric charge?  
   Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field producing +ve or -ve charge 

2. What are the types of electric charge?  
   The two types of electric charges are Positive charges and Negative charges.  
   a. Positive charge: If an atom or molecules have the protons and then electrons. 
   b. Negative charge: If an atom or molecules have the electrons than protons. 

3. How are charges produced?  
   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 and the objects with opposite charges attract each other and sometimes these kinds of materials stick together. This is called a static cling. 

4. Define Positive ion and negative ion. 
   Position Ion:  
   In a positive ion:   No. of Protons > No. of electrons 
   Negative Ion:  
   In a negative ion: No. of Protons < No. of electrons