current potential difference graphs

what does an I-V graph show

it shows how the current through a component changes as the potential difference across it changes

current (I) → y axis

potential difference (V) → x axis

what is an ohmic conductor?

A conductor where the current is directly proportional to the potential difference, provided the temperature stays constant.

What does the I-V graph for an ohmic conductor look like?

A straight line through the origin, this shows that the current is directly proportional to the potential difference.

Why does the I-V graph of a filament lamp curve?

As current increases the lamp gets hotter. It’s resistance increases so the current doesn’t increase proportionally with the potential difference

What does a filament graph look like?

A curve that gets less steep as potential difference increases

what is the behaviour of a diode in an I-V graph

in the forward direction: very little current flows until the potential difference reaches a certain value.

after this the current increases rapidly

in the reverse direction, almost no current flows

what does an I-V graph of a diode look like?

It is asymmetrical.

current mainly flows in one direction

what does the gradient of an I-V graph tell you?

For I against V graph the gradient 1/R not R. Gradient= I/V=1/R

steeper graph→ lower resistance

less steep graph→ higher resistance

what happens the resistance of a filament lamp as the temp increases?

It increases.

What does directly proportional mean?

Two quantities are directly proportional when one increases by the same factor as the other.

E.g. if potential difference doubles, current doubles