Applications of electricity Flashcards
function of a resistor
increases resistance of a circuit
function of a variable resistor
increases resistance of a circuit and and be changed
what is an ohmic conductor
current through an ohmic conductor is directly proportional to the potential difference across the resistor. resistance remains constant as the current changes.
what does the current-potential difference graph for an ohmic conductor look like?
a straight line through (0,0)
what does the current-potential difference graph for a filament bulb look like
a curved line
function of a bulb
produces light radiation
what does the current-potential difference graph for a diode look like
a curved line that increases significantly after a certain potential difference
function of a diode
allows current to only flow in one direction
function of an led
allows current to only flow in one direction, and produces light radiation
what happens to the resistance of a thermistor when the temperature changes
resistance decreases as temp increases
function of a thermistor
increases resistance of a circuit depending on the temp of the surroundings
what happens to the resistance of a LDR when the light intensity changes
resistance decreases as light intensity increases
function of an LDR
increases resistance of a circuit depending on the brightness of the surroundings
how are thermistors used
in circuits as thermostats
how are LDR’s used
in circuits to switch on lights when it gets dark
4 examples of non-ohmic conductors
diodes
filament bulbs
LDRs
thermistors
what happens to the current through components connected in series?
same current through each component
what happens to the total resistance through components connected in series?
total resistance of 2 components=sum of resistance of each component
what happens to the potential dif across components connected in series
total potential dif of the power supply is shared between the components
what happens to the current through components connected in parallel
current splits across the components
what happens to the total resistance of components connected in parallel
total resistance of two resistors is less than the resistance of the small individual resistor
what happens to the potential difference across components connected in parallel
the pd across each component is the same
what colour is the neutral wire
blue
what is the name of the blue wire in a plug
neutral
what colour is the earth wire
green and yellow stripes
what is the name of the green and yellow striped wire in a plug
earth
what colour is the live wire
brown
what is the name of the brown wire in a plug
live
what is the purpose of the neutral wire
completes the circuit
purpose of the live wire?
provides the alternating potential difference
purpose of the earth wire?
protects the circuit, stops the appliance casing from becoming live
what is the potential difference of a live wire
230V
what is the national grid
a system of cables and transformers linking power stations to consumers
what is the potential difference of mains electricity
230V
what is the frequency of mains electricity
50Hz
what type of current is mains electricity
alternating current
what is direct current
current flows in one direction around a circuit due to a direct potential difference
what is alternating current
current changes direction
why does the national grid transmit electricity at very high potential differences
less energy is lost which makes it more efficient
what happens at step-up transformers
potential difference increased
what happens at step-down transformers
potential difference lowered
why do we need step-down transformers
electricity has to be reduced to mains potential difference (230V) to be safe to use in homes.
