10.3.1—The principle of a potential divider circuit
- Syllabus
- 9702–2028–2029
- Objective
- 10.3.1
- Level
- AS
A potential divider shares supply voltage in proportion to series resistances
For series resistors R₁ and R₂ across supply V_s, the output across R₂ is V_out=V_s R₂/(R₁+R₂).
The output changes when one resistance changes; specify which resistor is measured across and account for loading by a connected device.
With equal resistors across 10 V, the midpoint is 5 V; replacing the lower resistor by a sensor shifts the output.
The output is not always half the supply; that occurs only for equal effective resistances and negligible load.
ConceptA-Level CAIE Physics AS