3. Charge on the parts of an atom Negative charge (-) No charge Positive charge (+)
4. Charged particles Adding or removing electrons results in charged particles. This can be caused by friction or contact. ++++++++ +++++ +++++++ ------- ----- -------- Positive Neutral Negative
5. 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.
6. 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
7. 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.
8. 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.
9. 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.
10. 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).
11. Circuit diagrams Symbols are used to represent the different parts of a circuit. The symbols are universal so everyone knows what they represent.
12. 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
13. 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.
14. 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.
15. Analysing Classify 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.
16. Conductors and insulators Note: Our body is a conductor. Hence, we must never touch electricity as it will flow through our body and may kill us.