This key facts covers Key Facts within I-V Characteristics for GCSE Physics. Revise I-V Characteristics in Extra Topics for GCSE Physics with 13 exam-style questions and 11 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 7 of 12 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
📋 Key Facts
- I-V graphs plot current (I) on the y-axis and voltage (V) on the x-axis
- A straight line through the origin means constant resistance (ohmic conductor)
- A curve that gets less steep means resistance is increasing (e.g. filament lamp heating up)
- Resistance at any point on an I-V graph = V/I at that point (NOT the gradient)
- A diode only conducts in the forward direction above a threshold voltage of about 0.6 V
- In reverse bias, a diode has very high resistance and almost no current flows
- The filament lamp graph is symmetric about the origin (same shape for both directions)
- Diodes are used for rectification — converting AC to DC
- Ammeter goes in series; voltmeter goes in parallel with the component
Practice questions for I-V Characteristics
What does an I-V characteristic graph show for a component?
Explain why the I-V graph for a filament lamp is not a straight line.
Quick recall flashcards
What is a diode used for?
Converting AC to DC (rectification), because it only conducts in one direction
What is an ohmic conductor?
A component where current is directly proportional to voltage at constant temperature. The I-V graph is a straight line through the origin