Study guides
Electrical Circuits
5 guides for this subject — how to prepare, what to practise, and how to know it has gone in.
A practice question
Choose an answer and it is marked, with the explanation. From Electrical Circuits Practice Questions: 8 Worked MCQs.
A 12 V ideal source is connected in series with 2 kΩ and 4 kΩ resistors. What is the current through the 4 kΩ resistor?
The series resistance is 2 kΩ + 4 kΩ = 6 kΩ, so I = V/R = 12/6000 = 0.002 A = 2 mA. The strongest distractor is 3 mA, which comes from incorrectly using only the 4 kΩ resistor and ignoring the other series resistor.
A spoken answer, marked
An examiner's question, answered out loud and marked criterion by criterion. From Electrical Circuits Viva Questions: Three Worked Practice Stations.
Examiner
A 12 V ideal source feeds a 2 kΩ resistor in series with a node connected to 4 kΩ and 6 kΩ resistors in parallel to ground. Find the node voltage and both branch currents, and explain your method.
You identified the reference node and treated the source as ideal.
ImproveSay explicitly that the 2 kΩ resistor connects the 12 V node to the unknown node.
You combined the parallel resistance correctly and found a consistent node voltage.
ImproveShow the conductance form of KCL so both branch currents are visibly included.
The voltage and branch currents have appropriate units and signs.
ImproveCheck that the two branch currents sum to the current through the 2 kΩ resistor.
A strong answerI will take the bottom rail as ground and call the unknown node voltage V. The 12 V source is ideal, so KCL at the node gives (12 − V)/2 kΩ = V/4 kΩ + V/6 kΩ. The right-hand conductance is 1/4 kΩ + 1/6 kΩ, so V = 12 × (2.4/4.4) = 6.55 V, to three significant figures. The 4 kΩ branch current is 6.55/4 kΩ = 1.64 mA, and the 6 kΩ branch current is 6.55/6 kΩ = 1.09 mA. Their sum, 2.73 mA, matches (12 − 6.55)/2 kΩ, which checks KCL.
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Guides
- How to Study Electrical Circuits: A Practical GuideA practical method for learning circuit analysis: organise your notes, solve problems systematically and practise recalling key relationships.
- Electrical Circuits Study Plan: A Practical Four-Week MethodA four-week electrical circuits study plan with focused sessions, circuit-analysis practice and a method for targeting weak topics.
- Electrical Circuits Flashcards: 18 Core Cards to PractisePractise 18 electrical circuits flashcards on circuit laws, components, AC values and equivalent circuits, with a method for grading each answer.
- Electrical Circuits Practice Questions: 8 Worked MCQsPractise eight electrical circuits MCQs on resistance, power, Kirchhoff’s laws, RC circuits and AC impedance, with worked explanations.
- Electrical Circuits Viva Questions: Three Worked Practice StationsPractise electrical circuits viva questions on nodal analysis, RC transients and AC phasors, with worked answers and a repeatable oral-exam method.
Studying electrical circuits? Build your electrical circuits board from your own notes — the cards, papers and lectures are written from it. Free plan: 20 cards, a paper, a lecture and a viva to try.
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