P3.2.4 graphs of p.d. and current Flashcards
what is the name of the graph that measures current against potential difference
a characteristic graph
what is the characteristic graph for a resistance wire or a resistor?
linear line that goes straight through the origin. Current is directly proportional to the p.d. as the resistance does not change as you change the potential difference.
what is Ohms law
current is proportional to potential difference if the temperature does not change.
what happens if the wire gets hotter?
the resistance varies and the graph is not a straight line
what happens if a non-linear circuit element is added.
the resistance is not constant / the graph is no longer linear
what does the characteristic graph of a diode look like?
sharp increase in current after potential difference rises
why does the diodes characteristic graph look this way?
because diodes allow the current to flow in only one direction.
what is a zero error
when the analogue meter does not read zero before you connect it, there will be an error in all measurements.
how can you tell if there is a zero error?
if the graph does not go through the origin (0,0)
