LEFT CLICK OR PRESS SPACE BAR TO ADVANCE, PRESS P BUTTON TO GO BACK, PRESS ESC BUTTON TO END LEFT CLICK OR PRESS SPACE BAR TO ADVANCE, PRESS P BUTTON TO GO BACK, PRESS ESC BUTTON TO END COMPUTER PRESENTATIONS FOR KS3 SCIENCE - PHYSICS ©2003, STEVE PARKER COMPUTER PRESENTATIONS FOR KS3 SCIENCE - PHYSICS ©2003, STEVE PARKER

1 1 KS3 SCIENCE - PHYSICS KS3 SCIENCE - PHYSICS Electrical Circuits Electrical Circuits

CIRCUIT DIAGRAMS 2 2

3 3 A circuit diagram shows the direction of the current and any components connected A circuit diagram shows the direction of the current and any components connected A A

CIRCUIT DIAGRAMS 4 4 Basic symbols for circuit diagrams are shown below Basic symbols for circuit diagrams are shown below A A X X M M V V

CIRCUIT DIAGRAMS 5 5 Basic symbols for circuit diagrams are shown below Basic symbols for circuit diagrams are shown below A A X X M M V V Cell Battery

Variable Resistor Variable Resistor CIRCUIT DIAGRAMS 6 6 Basic symbols for circuit diagrams are shown below Basic symbols for circuit diagrams are shown below A A X X M M V V Fixed Resistor Fixed Resistor

CIRCUIT DIAGRAMS 7 7 Basic symbols for circuit diagrams are shown below Basic symbols for circuit diagrams are shown below A A X X M M V V X X Bulb (either) Bulb (either) Switch (open/closed) Switch (open/closed)

CIRCUIT DIAGRAMS 8 8 Basic symbols for circuit diagrams are shown below Basic symbols for circuit diagrams are shown below A A X X M M V V M M V V A A Ammeter Voltmeter Motor

CONDUCTORS & RESISTORS 9 9

10 Materials which allow negatively charged electrons to move through them easily are called good “Conductors” Materials which allow negatively charged electrons to move through them easily are called good “Conductors” Metals are good conductors of electricity, and metal wire is used in circuits Metals are good conductors of electricity, and metal wire is used in circuits

CONDUCTORS & RESISTORS 11 Materials which allow negatively charged electrons to move through them easily are called good “Conductors” Materials which allow negatively charged electrons to move through them easily are called good “Conductors” Other materials, e.g. water, conduct electricity but are poor conductors Other materials, e.g. water, conduct electricity but are poor conductors

CONDUCTORS & RESISTORS 12 Materials which do not allow electrons to move through them at all are called “Insulators” Materials which do not allow electrons to move through them at all are called “Insulators” Insulators include rubber and china, and are useful for protection if there is an electrical fault Insulators include rubber and china, and are useful for protection if there is an electrical fault

CONDUCTORS & RESISTORS 13 If a material allows electrons to flow through it but slows them down, this is a “Resistor” If a material allows electrons to flow through it but slows them down, this is a “Resistor” If we have a resistor in the circuit, less current flows and the bulb is less bright If we have a resistor in the circuit, less current flows and the bulb is less bright

CONDUCTORS & RESISTORS 14 If a material allows electrons to flow through it but slows them down, this is a “Resistor” If a material allows electrons to flow through it but slows them down, this is a “Resistor” With a variable resistor in the circuit, we can change the current and the brightness With a variable resistor in the circuit, we can change the current and the brightness

SERIES & PARALLEL CIRCUITS 15

SERIES & PARALLEL CIRCUITS 16 There are two types of circuits, “Series” and “Parallel” There are two types of circuits, “Series” and “Parallel” A A Things in this circuit are connected in series, i.e. along a single path Things in this circuit are connected in series, i.e. along a single path

SERIES & PARALLEL CIRCUITS 17 There are two types of circuits, “Series” and “Parallel” There are two types of circuits, “Series” and “Parallel” Things in this circuit are connected in parallel, i.e. along two branches Things in this circuit are connected in parallel, i.e. along two branches A A A A

A A A A SERIES & PARALLEL CIRCUITS 18 Here there are two different paths, and current may travel down either Here there are two different paths, and current may travel down either

A A A A SERIES & PARALLEL CIRCUITS 19 Here there are two different paths, and current may travel down either Here there are two different paths, and current may travel down either The current may be different along each of the branches The current may be different along each of the branches

A A A A SERIES & PARALLEL CIRCUITS 20 But the current along the two branches always adds up to that at the start But the current along the two branches always adds up to that at the start E.g. if we start with 60A of current the two branches must add up to 60A E.g. if we start with 60A of current the two branches must add up to 60A 20A 40A 60A

SERIES & PARALLEL CIRCUITS 21 In a series circuit, the voltage across each component adds up to the voltage across the cell In a series circuit, the voltage across each component adds up to the voltage across the cell V V V V V V 100V 40V 60V

SERIES & PARALLEL CIRCUITS 22 In a parallel circuit, the voltage across each component is the same as the voltage across the cell In a parallel circuit, the voltage across each component is the same as the voltage across the cell V V V V V V 100V