Brainlag PlusThe I-V graphs of a resistor, a filament lamp and a diode, finding resistance from them, and the I-V required practical.
Three graphs to know
An I-V graph puts potential difference along the bottom and current up the side, with negative values for the supply connected the other way round.
Fixed resistor at constant temperature: a straight line through the origin. Current is directly proportional to p.d., so the resistance is constant.
Filament lamp: a curve that flattens off at both ends. As the current grows the filament heats up and its resistance rises.
Diode: no current at all in the reverse direction (very high resistance), then a steep rise once the forward p.d. passes about 0.6 V. Current flows one way only.
The rest of this lesson and its 8 practice questions are in Plus.
Screen 1 of 4, free to read.
- 8 exam-style questions, marked as you go, each with a worked solution
- The Series and parallel circuits simulation beside every question
- Anything you get wrong is saved to your flashcards