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ELECTRICITY
Value
of mains
supply = 230V
ELECTRICITY
Fuse is used as a
safety device
Prevents too much
current flowing in
circuit.
ELECTRICITY
Power of
appliances
measured in
watts (W)
ELECTRICITY
Plug wires – colours
Live – brown
Neutral – blue
Earth – green/yellow
Fuse in live position
ELECTRICITY
Double insulation – no earth
wire required as casing of
appliance is plastic –non
conductor
ELECTRICITY
Human being is a conductor
of electricity so do not touch
wires ,do not come into
contact with water with
electricity.
Electricity
PARTS
OF THE RADIO
1. AERIAL - PICKS UP ALL
SIGNALS
2. TUNER – SELECTS ONE
PARTICULAR SIGNAL
TELECOM
3.
DECODER – SEPARATES
CARRIER WAVE FROM
AUDIO WAVE
4. AMPLIFIER – MAKES
BIGGER COPY OF AUDIO
WAVE
TELECOM
5.
BATTERY – SUPPLIES
ENERGY TO AMPLIFIER
6. LOUDSPEAKER –
CHANGES ELECTRICAL
ENERGY TO SOUND
ENERGY
TELECOM
COLOUR
MIXING
3 PRIMARY COLOURS –
RED , GREEN , BLUE
TOGETHER MAKE WHITE
TELECOM
RED
AND GREEN GIVE
YELLOW.
RED AND BLUE GIVE
MAGENTA
GREEN AND BLUE GIVE
CYAN
TELECOM
GEOSTATIONARY
SATELLITES ARE AT A
HEIGHT OF 36 , 000Km
ABOVE THE EARTH
THEY HAVE A 24 HR ORBIT
TELECOM
SIGNALS
ARE MICROWAVE
AND TRAVEL IN A
STRAIGHT LINE TO AND
FROM THE SATELLITE.THEY
CANNOT CURVE IN THE
EARTH`S ATMOSPHERE
TELECOM
OPTICAL
FIBRES USED TO
CARRY INFORMATION BY
TOTAL INTERNAL
REFLECTION. LIGHT
TRAVELS AT A SPEED OF
200 , 000 , 000 M/S
ELECTRICITY

EQUATIONS
Q=IxT
V=IxR
P=IxV
P=E/t
 P = V2 / R
P = I2R
 RT = R1 + R2
 1 /RT = 1/R1 + 1/R2

ELECTRICITY
RULES FOR SERIES AND PARALLEL CIRCUITS
 VOLTAGE SPLITS UP IN A SERIES CIRCUIT
 CURRENT STAYS THE SAME IN A SERIES
CIRCUIT
 VOLTAGE STAYS THE SAME IN A PARALLEL
CIRCUIT
 CURRENT SPLITS UP IN A PARALLEL CIRCUIT

ELECTRICITY
VOLTMETERS MEASURE VOLTAGE AND
GO ACROSS THE COMPONENT
 AMMETERS MEASURE CURRENT AND ARE
WIRED IN SERIES WITH THE
COMPONENTS.
 CIRCUIT COMPONENTS INCLUDE
RESISTORS , BULBS ETC.

ELECTRICITY
MAINS ELECTRICITY
 WIRES IN THREE PIN PLUG
 1. BROWN LIVE
2. BLUE NEUTRAL
 3. GREEN / YELLOW EARTH
 FUSE IS A SAFETY DEVICE WIRED IN THE
 LIVE PIN
 EARTH WIRE NOT NEEDED FOR DOUBLE
INSULATED APPLIANCES , THEY HAVE A
PLASTIC CASING

ELECTRICITY
MAINS ELECTRICITY
 THREE TYPES OF CIRCUIT
 1. THE LIGHTING CIRCUIT 15A FUSE 2.
THE RING MAINS CIRCUIT 30A FUSE
3. THE COOKER CIRCUIT 45A FUSE
 ALL ARE WIRED IN PARALLEL IF ONE
GOES OUT THE OTHERS STAY ON LESS
WIRE USED SO MONEY IS SAVED

ELECTRICITY
ELECTRIC MOTORS
 COIL OF WIRE CARRYING CURRENT
SURROUNDED BY A PAIR OF MAGNETS
 THE MORE TURNS ON THE COIL AND THE
STRONGER THE MAGNET , THE FASTER
THE COIL GOES.

ELECTRICITY

TWO COILS OF WIRE WITH AN IRON
CORE , THE PRIMARY COIL AND THE
SECONDARY COIL
 TRANSFORMERS
 NP /NS = VP / VS
 IP x VP = IS x VS
HEALTH
TYPES OF THERMOMETER
 1. THE LAB THERMOMETER 2. THE
CLINICAL THERMOMETER BOTH LIQUID
IN GLASS THERMOMETERS 3. THE
DIGITAL THERMOMETER
 DIFFERENCE BETWEEN LAB AND
CLINICAL THERMOMETERS, SIZE,SCALE,
MAGNIFIER IN CLINICAL
THERMOMETER,KINK
