BRAINCAKEIV Graphs
A current-potential difference graph, or IV graph, shows how the current through a component changes as the p.d. across it is varied. The p.d. is reversed to find how the component behaves in both directions.
An ohmic conductor, such as a fixed resistor at constant temperature, gives a straight line through the origin. Its resistance is constant.
A filament lamp gives a curve that becomes flatter at higher p.d. As the current increases, the filament gets hotter and its resistance increases, so the current rises less for each extra volt.
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Key terms in this lesson
- Thermistor
- A component whose resistance decreases markedly as its temperature increases, because more charge carriers become available.
- Light dependent resistor
- A component whose resistance decreases as the intensity of light falling on it increases.
- Diode
- A semiconductor component that allows current to flow easily in one direction, forward bias, but has a very high resistance in the other, reverse bias.
- Threshold voltage
- The minimum forward potential difference across a diode, about 0.6V for silicon, needed before it conducts appreciably.
More in Electric Current
- Resistivity
- Superconductivity
- Electronic Components
- Investigating the Characteristics of Components
- Fixed Resistors
- Filament Lamp
- Thermistors and Light Dependent Resistors
- Diodes
All 20 lessons in Electric Current · All AQA AS-level Physics topics