Electricity Flashcards
(20 cards)
What is an LDR
Resistance decreases with light level
Variable resistor
Allow current to be varied
Thermistor
Resistance decreases with heat
Fuse
Melts when current is too high
Current
The speed of a flow of charge around a circuit
Potential difference
How much energy each charge has
Ohmic conductor
At a constant temp, current is directly proportional to the potential difference
Filament lamp
As current increases, resistance increases. Temp increases with current flow.
Diode.
Current flows when potential difference flows forward. Very high resistance in reverse
Series VS paralell
Series - there is only one path that a charge can flow around a circuit
Current is same through all components
Potential difference is shared between components
Resistance is sum of each component’s resistance
Parallel
A circuit that contains a junction where the current can split or join
Total current is sum of each component’s
current
Potential difference across all currents is the same
Resistance is less than the value of the smallest individual resistor
AC VS DC
AC
Alternating current repeatedly changes direction
DC
Only flows in one direction
UK plugs
Live: Brown
Neutral: Blue
Earth: Green and yellow stripes
230V 50HZ
Uses brass pins since the alloy is hard
Plastic casing is an insulator
Contains a fuse
What is the national grid
A series of cables and transformers which links power stations to customers
Why does electricity have a very high potential difference along the national grid
A high potential difference does not cause as much resistance of having a high current
Step up vs step down transformer
Step up transformer increases potential difference
Step down transformer decreases potential difference
How is static electricity made
When certain insulating materials are rubbed together, they become electrically charged
Force of friction is removing electrons from one material and moving them to the other
Is static electricity, which insulator is positively / negatively charged?
Negatively charged = gained electrons
Positively charged = lost electrons
What do electric field lines do
Show the direction a positive charge would move in the field
Opposite _____ and like charges _____.
attract, repel
Why does sparking happen?
Earthed conductor approaches charged object
Charges jump very quickly from charged object to earthed conductor
