10.2.5—Kirchhoff’s laws, a formula for the combined resistance of two or more
- Syllabus
- 9702–2028–2029
- Objective
- 10.2.5
- Level
- AS
Use Kirchhoff’s laws with equivalent resistances to reduce and solve simple networks
Combine series and parallel sections where possible, then apply junction current conservation and loop energy conservation to the remaining circuit.
Label branch currents and polarities before writing equations; a negative solved current only reverses the assumed direction.
Reduce two parallel branches first, then use the source loop equation to find total current and branch voltages.
Equivalent resistance simplifies terminal behaviour but does not erase the branch currents or internal voltage distribution.
ConceptA-Level CAIE Physics AS