NATURAL SCIENCES
Grade 9
Electrostatics, Electric Circuits, Resistance and Energy
What is Electricity?
Electricity is a form of energy that is associated with electric charges. It can exist in two main
forms: static electricity and current electricity.
Static electricity refers to charges that are not moving, while current electricity refers to
charges that flow through a circuit.
Structure of the Atom and Electrical Charge
All matter is made up of tiny particles called atoms. Atoms consist of three types of particles:
• Protons, which have a positive charge
• Electrons, which have a negative charge
• Neutrons, which have no charge
In solids, only electrons are able to move from one atom to another. This movement of
electrons is what causes objects to become electrically charged.
When an object gains electrons, it becomes negatively charged. When an object loses
electrons, it becomes positively charged.
Conservation of Charge
The law of conservation of charge states that electric charge cannot be created or destroyed. It
can only be transferred from one object to another. This means that the total charge before
and after a process remains the same.
Electrostatic Charge
Electrostatic charge is a build-up of electric charge on the surface of an object. These charges
remain stationary and do not flow like current electricity.
Electrostatic charge is measured in coulombs (C), although learners are usually not required
to calculate this at Grade 9 level.
Electrostatic Forces
Electrostatic forces are the forces that exist between charged
objects.
Objects with the same type of charge repel each other, while
objects with opposite charges attract each other. These forces
act over a distance and do not require the objects to touch.
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, Electric Fields
An electric field is the region around a charged object where it can exert a force
on another charged object.
Electric fields are represented using field lines. These lines show both the
direction and strength of the electric field.
Field lines always move from positive charges to negative charges. The closer the
field lines are to each other, the stronger the electric field in that area. Field lines
never cross one another.
Methods of Charging
Objects can become charged in three different ways.
Charging by friction occurs when two objects are rubbed together, causing
electrons to transfer from one object to another.
Charging by contact, also known as conduction, happens when a charged object touches an
uncharged object and transfers electrons.
Charging by induction occurs when a charged object is brought close to another object without
touching it, causing the electrons in the object to rearrange.
Electrostatic Discharge
Electrostatic discharge is the sudden movement of electric charge between two objects. This
often happens when there is a large build-up of charge.
A common example is the small shock you feel when touching a metal object after walking on
a carpet.
Lightning
Lightning is a natural example of electrostatic discharge on a
very large scale.
During a storm, charges build up inside clouds. Negative
charges collect at the bottom of the cloud, while positive
charges build up on the ground below. When the difference
between these charges becomes large enough, a discharge
occurs in the form of lightning.
Earthing
Earthing is the process of transferring excess charge safely into the ground.
This is important because it helps to prevent electric shocks and protects buildings and
electrical systems. Lightning conductors are an example of earthing, as they safely direct
lightning into the ground.
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Grade 9
Electrostatics, Electric Circuits, Resistance and Energy
What is Electricity?
Electricity is a form of energy that is associated with electric charges. It can exist in two main
forms: static electricity and current electricity.
Static electricity refers to charges that are not moving, while current electricity refers to
charges that flow through a circuit.
Structure of the Atom and Electrical Charge
All matter is made up of tiny particles called atoms. Atoms consist of three types of particles:
• Protons, which have a positive charge
• Electrons, which have a negative charge
• Neutrons, which have no charge
In solids, only electrons are able to move from one atom to another. This movement of
electrons is what causes objects to become electrically charged.
When an object gains electrons, it becomes negatively charged. When an object loses
electrons, it becomes positively charged.
Conservation of Charge
The law of conservation of charge states that electric charge cannot be created or destroyed. It
can only be transferred from one object to another. This means that the total charge before
and after a process remains the same.
Electrostatic Charge
Electrostatic charge is a build-up of electric charge on the surface of an object. These charges
remain stationary and do not flow like current electricity.
Electrostatic charge is measured in coulombs (C), although learners are usually not required
to calculate this at Grade 9 level.
Electrostatic Forces
Electrostatic forces are the forces that exist between charged
objects.
Objects with the same type of charge repel each other, while
objects with opposite charges attract each other. These forces
act over a distance and do not require the objects to touch.
1
, Electric Fields
An electric field is the region around a charged object where it can exert a force
on another charged object.
Electric fields are represented using field lines. These lines show both the
direction and strength of the electric field.
Field lines always move from positive charges to negative charges. The closer the
field lines are to each other, the stronger the electric field in that area. Field lines
never cross one another.
Methods of Charging
Objects can become charged in three different ways.
Charging by friction occurs when two objects are rubbed together, causing
electrons to transfer from one object to another.
Charging by contact, also known as conduction, happens when a charged object touches an
uncharged object and transfers electrons.
Charging by induction occurs when a charged object is brought close to another object without
touching it, causing the electrons in the object to rearrange.
Electrostatic Discharge
Electrostatic discharge is the sudden movement of electric charge between two objects. This
often happens when there is a large build-up of charge.
A common example is the small shock you feel when touching a metal object after walking on
a carpet.
Lightning
Lightning is a natural example of electrostatic discharge on a
very large scale.
During a storm, charges build up inside clouds. Negative
charges collect at the bottom of the cloud, while positive
charges build up on the ground below. When the difference
between these charges becomes large enough, a discharge
occurs in the form of lightning.
Earthing
Earthing is the process of transferring excess charge safely into the ground.
This is important because it helps to prevent electric shocks and protects buildings and
electrical systems. Lightning conductors are an example of earthing, as they safely direct
lightning into the ground.
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