electricity Flashcards
what is electrical current
the flow of electrons
units of current
amp
what is an insulator
a material that doesn’t allow electric currents
what is a conductor
a material that allows electric currents to pass through it
why can conductors conduct electricity
it has electrons that are free to move
what is potential difference
the difference of electrical potential between two points
unit of pot diff
volts
where do you put an ammeter
connected in series
where do you put a voltmeter
connected in paralell
what is resistance
a measure of how difficult it is for current to flow through a component.
how can the size of the current be affected
resistance
potential diff
unit of resistance
ohms
how can resistance be affected
length of wire
what is the relationship between current and voltage in a resistor
directly proportional
What effect will increasing the current through a filament bulb have on the graph
it will curve because the temp and resistance are rising
what is a diode
a component that only allows current to flow through it in one direction.
what is a rectifier
a component that turns an alternating current into a direct current
what is a thermistor
a component where resistance changes with its temperature.
what is an ldr
resistance changes with light intensity.
what happens when you increase the temp in a thermistor
resistance decreases
what happens when you increase the light intensity
resistance decreases
what is ohms law
The current through an ohmic conductor (at a constant temperature) is directly proportional to the potential difference across the resistor.
in an ohmic conductor the resistance
remains constant
current between components in series are
the same
resistance between components in series are
added up
how to find the total potential diff in series
add up the individual voltages of the cells
How are the voltages across components related to the battery voltage?
they sum together to give the battery voltage
how is current displayed in a parallel circuit
split between the branches
resistance in a parallel circuit is
The combined resistance of two resistors in parallel is less than the resistance of either of the two resistors by themselves.
how to work out the reciprocal of the total resistance
the sum of the reciprocals of the individual resistances
how is voltage shown in a series circuit
the same
what is mains electricity
50hz and 230v
what is the brown wire
live wire
what is the live wire
provides a current
what is the blue wire
neutral wire
what does the neutral wire do
completes the circuit
what is the yellow and green
earth wire
what is the earth wire
stops the appliance becoming live and has 0V
what is the national grid
the network of cables and transformers that connect power stations with houses and shops in the United Kingdom
what are step up transformers
increase the potential difference to 400,000 Volts.
why are step up transformers used
this reduces the current and how much heat is lost
increases efficiency
what are step down transformers
gets the electricity down to a safer voltage
what is a fuse
when the current gets too high the fuse melts and breaks the circuit
what happens when a case becomes live
it needs earthing
what can a charged rod do
attract a gentle stream of watere
what is static electricity
electrons transfer from one object to another
what does a charge object create
an electric field
what way do the electric field lines do on a positive
away
what ways effect the electric field
closer the object is to a charged object
higher the charge of the object
