Studied by 1 person
Alternating current
current flow consisting of charges that continually change direction
ammeter
a device connected in series with a component to measure the current that flows through it
amp ( A )
unit of current
Circuit breaker
A safety device that cuts off the power supply if a surge of current passes through it
coulomb
unit of charge
currents at a junction
the sum of current entering a junction must always equal the sum of currents leaving it
diode
a component that only allows current to flow in the forward direction
direct current
current flow consisting of charges flowing in a single direction only
earth wire
the green and yellow striped safety wire connected to metal casings that prevents an appliance from becoming live
electric current
the rate of flow of charge
energy transfers in circuits
electrical energy is transferred to thermal energy when current does work against a resistance
filament lamp
a light emitting component consisting of an enclosed metal filament
fuse
a safety device consisting of a thin metal filament that melts and cuts off a power supply if there is a surge in current
Light Dependent Resistor
A light sensitive component whose resistance decreases as its temperature increases
Light emitting diode
a device that gives out light when a current flows through it. Current can only flow in one direction and a minimum voltage must be applied across it before it lights up
live wire
the brown coloured wire that carries the alternating current from the supply in a mains power supply
mains electricity
An a.c supply that, in the UK, has a frequency of 50 Hz and a value of 230V
Neutral Wire
the blue coloured wire that completes the circuit in a mains power supply
Ohmic Conductor
A conductor whose current flow is directly proportional to the potential differance across it, when kept at a constant temperature
Ohms
Unit of resistance
Ohm’s law
the current flowing through an Ohmic conductor at a constant temperature is directly proportional to the potential differance across it
Parallel
Components connected in parallel had the same voltage across each component an the total current is equal to the total sum of currents flowing through each component
potential differance ( voltage )
the energy that is transferred per unit of charge between 2 points in a circuit
power
the rate at which an appliance transfers energy
power for a circuit component =
current passing through it x voltage across it
resistance
a measure of the opposition to current flow
resistors in parallel
the total resistance is less than the lowest individual resistance
resistors in series
the total resistance is equal to the sum of the resistances of the individual resistors
series
components connected in series have the same current passing through but share the total voltage of the power supply
thermistor
a temperature dependent component, whose resistance increases as temperature decreases
volt
the unit of potential differance
1 volt =
1 joule / coulomb
volt metre
a device that is connected in parallel with a component to measure the potential differance across it
watt
the unit of power
energy transferred =
charge moved x voltage
charge =
current x time
voltage =
current x resistance
resistors heat up when used because …
… the electrons carrying the charge collide with the ions in a lattice in the resistor, increasing the kinetic energy, increasing the temperature
energy transferred =
current x voltage x time
power =
energy transferred / time taken
electrical power =
current x voltage
electrical power =
current ^ 2 x resistance
Note 
Flashcard (90)