Electricity

All matter is made of

electron

neutron

proton

atoms

Charge on the parts of an atom

Negative charge (-)

No charge

Positive charge (+)

Charged particles

• Adding or removing electrons results in charged particles. This can be caused by friction or contact.

• ++++++++ +++++ +++++++

------- ----- --------• Positive Neutral Negative

Activities results

• Plastic rod + COTTON- Bent water least• + WOOL- Bent water most• +SILK- Bent water next • Balloon + WOOL- Balloon moves towards the

wool• Balloon + Balloon- Balloon repelled each other• Picking up rice= 6 grains max.

Important concepts of electric charge

• Opposite charges attract each other• Like charges repel each other• Objects with more electrons than protons are negative

• Objects with less electrons than protons are positive• Objects with the same number of electron and

protons are neutral• Only electrons move when an object is rubbed• Electricity is caused by electrons

What do atomic particles have to do with electricity

• Electricity is the result of a flow of electrons. All matter is made of atoms; this means matter is full of electrons. This is important because whenever an electric current appears in an object, the electrons already present within it are forced to flow.

Static vs Current Electricity

• Static electricity is when the charge (electrons) builds up in an object and stay put (are stationary) until something come into contact with it.

• An electric current is when the electric charge (electrons) flows through a path (circuit). This is the type of electricity that powers the appliances in our homes.

Electric circuits

• When electricity flows through an electric circuit, electrical energy is changed into sound, light, heat or kinetic energy by the appliance it is flowing through.

• An electric circuit must have a power supply (battery or powerpack), a conducting path (the wires the charge flows through) and a load (appliance).

Circuit diagrams• Symbols are used to represent the different

parts of a circuit. The symbols are universal so everyone knows what they represent.

• The flow of electric charge is called an electric current.

• The unit that measures electric current is amperes or amps

• We can think of it as counting how many electrons pass a certain point each second

• The energy of the electric charge is called the voltage. It is measured in volts

• We can think of this as how many hats each electron has and can therefore give away to an appliance in the circuit.

Conductors and Insulators

• Conductors• Conductors are materials that electricity easily passes through,

that do not resist the flow of electricity. Conductors conduct electrical current very easily because of their free electrons.

• Examples are copper, aluminium, steel, silver, gold. Not all materials conduct electricity equally well.• Insulators• Insulators are materials that resist the flow of electricity, so

electricity does not easily pass through. Examples are plastic, wood, rubber, cloth, air, glass. Some materials are better electricity insulators than others.

AnalysingClassify the following materials into electrical conductors and insulators: iron nail, glass rod, rubber band, wooden stick, aluminium foil, chalk, plastic ruler, copper wire, liquid mercury

Conductors: iron nail, aluminium foil, copper wire, liquid mercury.Insulators: glass rod, rubber band, wooden stick, chalk, plastic ruler.

Conductor Insulator

A material that allows electricity to pass through it

A material that does not allow electricity to pass through it

Metals Non-metals

Examples: copper, iron, aluminium Examples: plastic, rubber, glass, wood

Note: Our body is a conductor. Hence, we must never touch electricity as it will flow through our body and may kill us.

Conductors and insulators