P2 Flashcards
What are amps?
The unit of current
What are Coulombs?
The unit of charge
What is a diode?
A component that only allows current to flow in one direction. They have huge resistance in the reverse direction
What is the earth wire and what does it do?
The green and yellow striped safety wire
It prevents an appliance from becoming live
What are electric field lines?
Lines representing an electric field that point in the direction in which a positive charge would experience an electric force
What is an electrical field?
A region in which charge will experience a non contact, electric force. All charged forces have an electric field around them- it’s stronger the closer to the charge you are
What is an electrical current?
The rate of flow of electrical charge- is value is the same at any position in a single closed loop
What is electrical work?
When charge flows in a circuit, electrical work is said to be done
What is a filament lamp?
Light emitting component that consists of metal filament- the resistance increases as the temperature of the filament increases
What does insulation mean?
The coating around power cables that prevent electrocution- they’re colour coded for easy identification
What is a LDR?
Light Dependent Resistor- a light sensitive component whose resistance increases as the temperature decreases
What is the live wire?
It’s the brown coloured wire that carries the alternating current from the supply in a mains power supply
What is the mains electricity frequency and voltage in the UK?
230V
50Hz
(It’s A.C.- alternating current)
What is the neutral wire?
The blue coloured wire
It completes the circuit in a mains power supply
What is a non contact force?
A force experienced between two separate forces (e.g. gravity)
What are ohms?
The unit of resistance
What happens to the current and potential difference in a parallel circuit?
Components are connected in parallel- they have the same potential difference across each component. The total current is equal to the sum of currents flowing through each component.
What is potential difference?
The product of a component’s resistance and the h magnitude of the current flow through it
What is the difference between resistance in a parallel circuit compared to resistance in a series circuit?
PARALLEL- total is always less than that the resistor with the least individual value
SERIES- Total resistance is always the sum of all resistances in each individual component
What is the current and voltage like in a series circuit?
The components have the same current flowing through them, but they equally share the total potential difference from the supply
What are step down transformers?
Devices between the transmission cable and the consumer that LOWER potential difference levels so it’s at a safe and usable level
What are step up transformers?
Devices that increase the potential difference generated at power stations so the power transmitted along the transmission cable is higher
What is the National Grid?
The network of power stations, transformers and cables that connect consumers to power stations
What does a thermistor do?
It’s a temperature dependent component, whose resistance increases as its temperature decreases
What is resistance?
How hard it is for the current to flow
What is current?
The rate of flow of charge
What is direct current?
Current that only flows in one direction
What is alternating current?
Where the direction of the current flow continually changes
Where are step up transformers used?
They’re used between power stations and power lines
Where are step down transformers used?
They’re used between power lines and houses
What are power lines?
Lines that transports current at very high voltages (to reduce energy loss) from power stations to houses
What happens to the resistance of a thermistor as temperature increases?
The resistance of a thermistor decreases as the temperature increases.
What is a potential use for a thermistor?
A thermistor could be used to make a thermostat keep a building at a certain temperature.
What happens to the resistance of an LDR as light intensity increases?
The resistance of an LDR decreases as light intensity increases.
What is a potential use for an LDR?
An LDR could be used to switch on lights when it gets dark.
What is the National Grid made up of?
The National Grid is made up of cables and transformers linking power stations to consumers.
What is the purpose of step up transformers in the National Grid?
Step up transformers are used to increase the potential difference for the transmission cables.
What is the purpose of step down transformers in the National Grid?
Step down transformers are used to decrease the potential difference for consumers.
What type of current does mains electricity supply?
Mains electricity supplies an alternating current.
What is the frequency of the mains supply in the UK?
In the UK, the mains supply has a frequency of 50Hz.
What is the voltage of the mains supply in the UK?
The mains supply in the UK is about 230 V.
