10.3.4—The use of thermistors and light-dependent resistors in potential dividers
- Syllabus
- 9702–2028–2029
- Objective
- 10.3.4
- Level
- AS
A thermistor or LDR in a potential divider converts temperature or light into a voltage signal
A sensor resistor in a potential divider changes the output voltage when temperature or light intensity changes its resistance.
First state the sensor trend, then identify which resistor the output is measured across; the same resistance change can raise or lower output depending on placement.
An NTC thermistor lowers its resistance when heated; an LDR lowers resistance in brighter light. Both can trigger a voltage threshold in a divider.
The sensor trend alone does not determine output direction—circuit arrangement and loading matter.
ConceptA-Level CAIE Physics AS