P3 - circuits Flashcards
What does an ammeter measure
current flowing through a circuit
how should an ammeter be placed in a circuit
in line with the component
what does a voltmeter measure
potential difference (p.d) across components
how should a voltmeter be placed in a circuit
parallel with component
what is a diode made from and what is it useful for
made from a semiconductor material e.g. silicon and is useful in radio receivers
what is an LDR and what is it used for
(light dependant resistor)
light up resistance down
L.U.R.D
used in outdoor lighting
what is a thermistor and what is it used for
temperature up resistance down
T.U.R.D
used in thermostats and irons
how are componants connected in a series circuit
in a line
what happens to p.d across a series circuit
p.d is shared between componants
pd across circuit = p.d of power supply
what happens to current in a series circuit
same everywhere
determined by p.d of power supply and total resistance of circuit
what happens to resistance in a series circuit
resistance adds up
total resistance = sum of individual resistances
what happens in series circuit if resistance of one componant changes
potential difference across all componants change
how are componants connected in a parallel circuit
seperatly connected
what happens to p.d across componants in parallel circuit
p.d is the same across componants
what happens to current in a parallel circuit
shared between branches
total current flowing round circuit = total of all currents through separate branches
what happens to resistance in a parallel circuit
when 2 resistors connected in parallel then total resistance decreases
( each resistor creates an extra path in which charge can flow so more charge flow = smaller overall resistance )
what is the p.d between 2 points
its the energy transferred by 1 coulomb of charge between the points
what does power tell you
how much energy it transfers per second
