Electricity ?? Flashcards
Where do the earth , live and neutral wire go ?and what are their colours ?
Earth wire - top of the plug ⚠️♻️??
Neutral- left of the plug ?????
Live -right of plug next to fuse ???????
Describe the live wire and its function
The supply of electricity from the national grid
Describe the neutral wire
Its a return wire , the electricity flows away from it
Describe the function of the earth wire
It is a low resistance connection to the earth . No current should usually flow through it . However if a live wire touches the metal casing of an appliance then the current will flow through the earth wire and blow the fuse to stop the appliance from electrocuting the user
What is a fuse ?
A thin wire in a glass or ceramic tube and when the current gets to high the wire melts and breaks the circuit
Describe a circuit breaker
They are resettable and have a magnetic or heating effect that means when the current is too high the circuit is broken
where are fuses and circuit breakers connected to in the plug
The live wire
What is a double insulated appliance ?
An appliance that has a outer casing made of an insulating material , normally plastic .nothing metallic is on the outside for the owner to possibly touch
What is the mains voltage supply in the u.k ?
230v
Describe the relationship between power current and voltage
Current ✖️voltage
What are the units for power , current and voltage
Current - amps
Voltage- volta
Power - watts
What the equation for energy transferred ?
Energy transferred = current x voltage x time
What are the two possible units for energy in electricity ?
Joules
Kilowatt-hour
What current do batteries supply ?
Direct current - the current is flowing in the same direction
What current does the main supply ?
Alternating current - fluctuates at 50hz
What is a series circuit ?
A series where all the components are connected end to end
The current is the same everywhere
The voltage (potential difference) is split across the components and should equal the voltage of the power supply
What is a parallel circuit ?
The components are connected in branches
The voltage (potential difference ) is the same
The current splits up so that the sum of the currents of each branch is equal to the power supplied by the battery
Why are christmas trees often connected in series ?
So that small low voltage bulbs can be used -but
If one bulb fails they all fail
What is current ?
The rate of the flow of charge
What is the relationship between charge , current and time
Current. ✖️ Time
What is current in solid metallic conductors ?
Its the flow of negatively charged electrons
They flow against conventional direction as the negative electrons will flow to the positive terminal
How do you place an ammeter / voltmeter in a series ?
An ammeter goes into the circuit and the voltmeter goes in parallel
What is the equation for resistance
Current ✖️ resistance
Describe the graphs for the resistance of
A) a wire at constant temperature
B) a bulb
C) a diode
A) a straight diagonal line ? (not the beginning bit but the long line )
B)a line that curves eventually
C)starts at 0 then around 4 volts it goes up very quickly
What is an ldr
A light dependant resistor that resistance drops when there is more light .
What is a thermistor ?
A thermistor is a component whos resistance drops As the temperature increases