9.3.3—The I–V characteristics of a metallic conductor at constant temperature, a
- Syllabus
- 9702–2028–2029
- Objective
- 9.3.3
- Level
- AS
A metallic conductor at constant temperature has a straight-line I–V characteristic through the origin
For an ohmic metal kept at constant temperature, current is proportional to voltage, so the I–V graph is a straight line through the origin.
The gradient of an I–V graph is 1/R, whereas the gradient of a V–I graph is R. State which axes are used.
Doubling voltage on a constant-temperature 4 Ω wire doubles current from 0.5 A to 1.0 A.
A curved I–V graph does not mean the device has no resistance; it means resistance changes with operating point.
ConceptA-Level CAIE Physics AS