chapter 4 Flashcards
what is electric current
the flow of electrical charge
what is potential differnce/voltage
the driving force that pushes the charge round
what does Q=IT mean
charge=current*time
whats the formula that links potential differnce and current
potential
differnce(v)=current(A)*resitsance(ohms)
what do ohmic conductors have
a constant resitance
whats not an ohmic conductor
diode and a filiment lamp
explain the IV graph of an ohmic conductor
The current is directly proportional to to potential differnce so you get a straight line
explain the IV graph of a filament lamp
as the current increases the temprrature of the filamnet increases, so the resistance increases. This means that less current can flow cauasing the graph to curve.
explain the IV graph of a diode
current will only flow through a diode in one direction beacuse it has a very hight resistance in the reverse direction.
what is LDR short for
light dependent resitsor
what happens to a LDR in bright light
the resistance falls
what happens to a LDR in darkeness
the resistance is the highest
what is a thermistor
a temperatur dependent resistor
what happens to a LDR in hot conditions
the resistance drops
what happens to a LDR in cool conditions
the resistance goes up
in a series circuit what happens to potential differnce
its sharred
how do you work out voltage in a series circuit
you add up all the volt meters
in a series circuit what happens to current
its the same everywhere
in a series circuit how do you work out resistance
add up all the resistors
in a parallel circuit what happens to potential difference
its the same across all components
in a parallel circuit what happens to current
its shared
what happens if you add a resistor to a parallep circuit
the resitance goes down
