2.  All matter is made of tiny particles called atoms.  Atoms are made of 3 different types of particles: 1. Protons 2. Neutrons 3. Electrons

3. + - - Electron Neutron Proton Nucleus

4.  A neutral atom has the same number of protons as electrons. Eg. A neutral oxygen atom has 8 protons and 8 electrons.

5.  Electrons can be removed from an atom, resulting in a positively charged atom. - - + + Neutral Positive

6.  Electrons can also be added to an atom, resulting in a negatively charged atom. - - + Neutral Negative -

7.  An atom with an uneven number of protons and electrons is called an ion.  Electrons can be separate from atoms and can move freely within and between certain substances.  This is why metals conduct electricity.

8.  Electricity is a convenient type of energy that travels very fast and can be transformed into a variety of other types of energy.

9.  There are two types of electricity. Static Electricity Current Electricity

10.  Static E occurs within insulators.  When the insulator is rubbed electrons are either added or removed, and the object is charged. + -

11.  When a plastic rod is rubbed with a wool cloth, the rod will lose electrons to the cloth and become positively charged.  The wool becomes negatively charged. + + + + + + - - - - - -

12.  Static electricity is caused by a surplus or deficiency of electrons in an object.  The object holds stored electrical energy. - - - - - -

13.  If two objects have opposite charges they will attract each other.  If they have the same charges they will repel. +- --

15. + + + + + + + + + + + + - - -- - - - - - - - - -

16.  Electrical currents happen when free electrons travel from an area which is negatively charged to an area which is positively charged.  Electricity needs a continuous pathway (circuit) in order to flow.

17.  A substance like copper has free electrons and is an electrical conductor.  Plastic is said to be an electrical insulator because it does not have free electrons.

18. ComponentSymbol Wire Single Cell Battery of Cells Open Switch Closed Switch Lamp Fuse

19.  A circuit consists of at least 3 main parts: 1. An energy source (e.g.. battery). 2. An energy user (e.g.. light bulb). 3. A complete conducting pathway (wires)

20.  Draw a simple circuit showing one light bulb controlled by a switch and powered by 2 cells.

21.  When electrons flow around a circuit they create current.  We can measure the amount of electrons flowing in a circuit with an ammeter.  The symbol for current is I, because it describes the intensity of the current.

22.  The ammeter measures in units called amperes (or amps) and is represented by the symbol A.  In circuit diagrams we represent an ammeter by the symbol: A

23. A ----

24.  An ammeter must be connected in series at the point where you wish to measure the current. A

25.  There are 2 types of current:  Direct Current (DC) – Electrons flow in only one direction. (E.g. Battery powered devices)  Alternating Current (AC) – Direction changes 50 times a second. (E.g. Electricity from mains)

26.  Current in a circuit carries electrical energy.  Electrons gain energy from the energy source and lose energy from the energy users, where it is converted into other forms.

27.  Voltage gain – the increase in electrical energy.  Voltage loss – the decrease in electrical energy.  We represent the gain or loss in voltage by the symbol V.

28.  The unit for voltage is the volt and can be measured with a voltmeter.  In circuit diagrams we represent an voltmeter by the symbol: V

29.  A voltmeter can only measure the change in voltage so it must be connected in parallel around a lamp or battery. V

30.  The amount of voltage lost at an energy user is equal to the amount of voltage gained from the batteries.  In a series circuit the voltage loss is shared between components.  In parallel the voltage loss is the same in both components.

31.  Conductors are materials that allow the flow of electric charge. Metals are good conductors.  Insulators are materials that do not allow the flow of electric charge. Plastic is an example of a good insulator.

32.  It is the delocalized electrons involved in metallic bonding that allow metals to conduct electricity.  The delocalized electrons are free to flow through the metal and so carry a current.  Insulating materials do not contain free electrons and so current is unable to flow.