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Current-potential difference graphs

1) for a filament bulb

  • the line CURVES away from the axis labelled current.
  • so the current is not directly proportional to the potential difference (not a straight line) : so it DOES NOT obey Ohm's Law= it is a non-ohmic conductor.
  • RESISTANCE increases as the CURRENT increases.
  • the resistance of the filament bulb increases as the TEMP increases -->

when the current is passed through- there are free electrons flowing through and around the metal atoms -->

as the temperature increases= metal gets hotter = the ions in the metal filament vibrate faster and gain energy=      

which means they resist the  passage of electrons through the filament more.

and therefore results in an INCREASED RESISTANCE- (shown


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