electricity, primary science

1. Electricity

2. CONDUCTORS
Are MATERIALS that allow charges
That allow charge to easily FLOW
Most common Metals Graphite

3. INSULATORS
This makes them VERY POOR
In INSULATORS electrons are
they can move BUT cannot flow
ANCHORED to the atoms
conductors
..
Glass Wood Plastic Rubber

4. Switches
are used to open or close an
There are many different
electric circuit
types:
Push-to-break
Push-to-make
Interrupter

5. Current Electricity
The switch a batteryclosed
Charges current to flow
By using must be cell
Before theybe PUSHED
For a must can
When the switch stops
The current is opened

6. Current Intensity
- +
A
AIsThepass each point in the
It is Currentof the series
acoulomb ammeter of
Using an is measured
connected in flow
Thatmeasureevery second
compound unit is replaced
It 1 the number Intensity
In thisoften thesecond science
Asis The Every ampere or amp
Although CONVENTION from
CURRENT FLOWSflow
is case
BYCurrent of coulombs
electrons in
case FROM
chargeaaroundword
by single a circuit
circuit
= 1 amp
+
- +
-
Unit: coulombs/second c/s
A
amps

7. Current Intensity
The current depends on the voltage
The brighter the light bulb
The bigger current
voltage
1 cell 2 cells
1 amp = 2 amp =
1coulomb/sec 2coulomb/sec
A A

8. The cell (or battery)
Which helps to push charge around
Provides the voltage
the circuit
And Toreactthe aare
These acquirecell
Thisacquire negative
ToThe voltaic more
Thecauses with the
the less reactive
electrodes
+ Immersed in an acid
Two electrodes
+ -- DIFFERENTcharge
positive metal
reactive metals
metal
consists of
charge
acid
+ --
+
+ - The build up of charge
Electrical potential
Between the
This DIFFERENCE in
E.M.F or (voltage)
A is also called the
+ -
+ - electrodes
results in
energy
Cathode Anode

9. The cell
The common alkaline cell
Depends on the materials used
The voltage produced by a cell
is made of
for the electrodes
Manganese
Oxide Cathode
This combination
Results in an
Of about 1.5 V
Alkaline E.P.D. (Voltage)
of electrodes
electrolyte
Zinc Anode

10. The battery
IsAs combinationseries
a the word in of cells
Connected suggests,
Connectedflatseries
The3 x 1.5 V cells
Is 4.5 V in pack

11. Electrical Potential Difference
Voltmeters are connected in parallel
Is measured using a voltmeter
6V
V V
Circuit symbol
6V Cell
V 6V

12. Resistance
as is thepass through a the flow of
it they opposition to conducting
ALL CONDUCTORS have resistance
material
charges
The electrons collide with vibrating
and the conductor gets hot
and this generates heat
atoms as they move

13. Resistance
Depends on
The dimensions of the conductor
Short
Thick
Long
Thin smaller
bigger
conductor resistance

14. Resistance
Depends on
The conductor material
Nichrome
Iron
Has more
resistance than
Copper
Iron

15. Resistance
change HIGH resistance material
Use you want a conductor to
If a electrical energy into heat
Nichrome
or
Tungsten

16. Resistance
change electrical energymaterial
If Use a LOW resistance into heat
you DON’T want a conductor to
Aluminium
or
Copper

17. Light Bulbs
have highchange
They resistances
Electrical Heat Light
Energy Energy Energy

18. Connecting light bulbs: IN SERIES
The resistance in the circuit
Each time a light bulb is connected
The lightlightcurrent flows
All If a light bulb blows off
A the bulbs grow dimmer
smaller bulbs turn
INCREASES
in SERIES
A
0.33amp
0.5amp
1 amp

19. E.P.D. in series circuits
The sum of the E.P.D across each
The EMF of the cell
Equals
component
Cell EMF= 6V
V V V
2V 2V
3V
6V 2V
3V

20. Connecting light bulbs: IN PARALLEL
The current taken each lightbattery
Eachbrightness ofbulbin the bulb is
The time a light from each light
current flowing is connected
If a light bulb blows
bulbincreases
inis unchanged
unchanged
PARALLEL
A
3
2
1 amp
1amp 1amp 1amp

21. E.P.D. in parallel circuits
Each timeThe EPD of theisit
The component cell
a e.m.f. across connected
equals
emf = 6V
6V 6V 6V
V V V