Electricity Flashcards
What is electrical charge measured in
Couloms
What does 1 Amp of current equal
1 Coulomb of charge per second
What is the equation of energy transferred by a component
E = Q x V
What is resistance
The potential difference required to drive a current through a component
What is resistance measured in
Ohms
What is a potential difference / Current graph for an ohmic resistor
It is directly proportional
How does current flow in a diode
One direction because a diode has a very high resistance in the reverse direction
Why are diodes useful in circuits
Controlling the flow of the current
When does an LDR have a high resistance
Dark conditions
What are the uses of LDR
Phones and garden lamps
What causes the resistance of a thermostat decrease
If the temperature increases
What is the equation linking energy, power and time
Energy =power x time
What is power in relation to energy
Power is the rate of energy transfer
What equation links power, current and resistance
Power = current^2 x resistance
What type of current is from a cell
Direct current
What is direct current
Current that flows in a single direction
What type of current is mains electricity in the UK
Alternating current
What is alternating current
Current that is constantly changing direction
What is the advantage of alternating current
It is easy to use a transformer which can change the potential difference
What is the frequency of alternating current in the UK
50 Hz
What’s the potential difference of main electricity
230 V
What metal are the three core cables made of and why
Copper as it is a good conductor of electricity
What’s the coating of the cable made of and why
Plastic as it doesn’t conduct electricity
What’s the name of the brown wire
Live Wire
What is the function of the live wire 
It carries the alternating potential difference of 230 V and it is also connected to a fuse in the plug
What is the name of the blue wire
Neutral wire
What is the function of the neutral wire
It completes the circuit and has a potential difference of 0 V
What’s the green yellow wire called
Earth wire
What’s the function of the Earth wire
It’s the safety wire to stop the appliance from becoming live
What happens when someone touches a live wire
The current will flow through the body into the Earth causing them to be electrocuted
What’s the route from a power station to the Home
It goes from the power station to step up transformer to high voltage cables then to step down transformers
Why is the energy lost in the power cables
The resistance of wires
How can energy loss from power cables be reduced
Building power stations near to homes
