THE EXAMS POINTSeries and parallel circuits
Begin at the centre. Explore a branch, explain its connection, then test your recall. Tap any branch heading to fold or expand it.
In recall mode, focus or tap a branch to reveal its explanation. Branches group related ideas; they do not imply a chronological sequence.
Series and parallel circuits
01 · Series
Same current through each component; Rₑq = R₁ + R₂ for two resistors.
02 · Parallel
Same potential difference across branches; 1/Rₑq = 1/R₁ + 1/R₂.
03 · Circuit model
Ideal wires and source; resistor values are positive and ohmic in this model.
Connect the branches
Trace whether current has one path or several branches. Compare resistor connections, not just their positions on the drawing.
Avoid the exam trap
Equal branch voltage in parallel does not imply equal branch current when resistances differ.
Test yourself: For two equal resistors R in parallel, what is the equivalent resistance?
R/2. Their conductances add, so the equivalent resistance is smaller than either resistor.
A concise revision aid with simplified connections. It supports the full chapter and primary references; it does not replace them.