Electricity Flashcards
What is an electric current?
The flow of electrical charge
What is current measured in?
Amps
What is electric charge measured in?
Coulombs
What is the resistance?
A measure of how it resists the flow of charge
What happens when the resistance is high?
Difficult for charge to flow
Lower the current
What is resistance measured in?
Ohms
What does potential difference tell us?
The difference in electrical potential from one point in a circuit to another
What can potential difference be thought of as?
Electrical push
What happens if the potential difference is bigger across a component?
The flow of charge is greater through the component
The bigger the current
What is potential difference measured in?
Volts
What do potential difference-current graphs show?
The relationship between potential difference and current for any component
What is an ohmic conductor?
A resistor in which the current is directly proportional to the potential difference at a constant temperature
How will current through a diode?
In one direction
What happens as the resistance of a thermistor decreases?
The temperature increases
What happens as light intensity increases in LDRs?
The resistance decreases
What happens as the current through a filament lamp increases?
The temperature increases
What are the two types of circuit?
Series
Parallel
What does the power of a device depend on?
The potential difference across it and the current flowing through it
What is a direct current?
Has a potential difference that is always positives or always negative
Used in batteries
What is an alternating current?
Has a potential difference that alternates from positive to negative
Used in mains electricity
What V and Hz used in the UK mains?
230V, 50Hz
What colour is the live wire?
Brown
What colour is the neutral wire?
Blue
What colour is the earth wire?
Green and Yellow stripes
What voltage goes through the live wire?
230V
What voltage goes throught the neutral and earth wire?
0V
What does the live wire do?
Carries current to the appliance
What does the neutral wire do?
Carries current away from the appliance
What does the earth wire do?
Stops the exterior of the appliance becoming live
What is power?
The rate at which energy is transferred or work is done
What is efficiency?
The ratio of useful energy out to total energy in
How do you increase the efficiency of an energy transfer?
Reduce the amount of waste energy
What is the national grid?
A system of cables and transformers linking power stations to homes and businesses
What does the power station do?
Transfers the energy supply into electrical energy
What do step up transformers do?
Increase potential difference from the power station to the transmission cables
What do transmission cables do?
Transfer the electricity
What do step down transformers do?
Reduce the potential difference
What happens when insulating materials are rubbed together?
They become electrically charged
What does the friction do when two insulating materials are rubbed together?
Moves negatively charged electrons from one material to another
What is an object with no conducting path referred to as?
Isolated object
What happens as the charge of an isolated object increases?
The potential difference between the object and the earth increases
What kind of force is an electro static force?
Non-contact
What can electrostatic forces be?
Attraction or repulsion
What happens when two objects have the same charge?
The repel
What happens when two objects have a different charge?
They attract
What does a charged object create?
A electric field around itself
What does the strength of an electric field depend on?
The distance from the object
The amount of charge
