How to study this deck

Electrical circuits questions often test whether you can choose the right relationship, apply it with consistent signs and units, and interpret the result. A flashcard can help you retrieve a formula or rule quickly, but it cannot replace working through circuit diagrams and calculations. Use this deck to secure the building blocks, then practise applying them to unfamiliar circuits.

Study one card at a time. Read the question, say or write a complete answer, and only then reveal the back. Grade yourself against what is actually written—not what you meant to say. Use Again if you could not retrieve it or made a major error; Hard if you needed substantial effort or missed an important condition; Good if you answered correctly without help; and Easy if the answer was immediate and precise. The platform uses your grade to schedule later reviews.

The cards below move from circuit laws to components, AC quantities and equivalent circuits. Keep a calculator nearby for the numerical cards, but say the relationship and units as well as the result. For example, “31.4” is incomplete if the question asks for inductive reactance: the answer is 31.4 Ω.

MySummaries builds this deck from a revision board, so the question-and-answer pairs can sit alongside the notes they came from. Here is one electrical circuits deck to work through:

Cards — Electrical Circuits18 due

A 12 V supply is connected across a 4 Ω resistor. What current flows?

3 A, from I = V/R = 12/4.

All 18 cards
A 12 V supply is connected across a 4 Ω resistor. What current flows?3 A, from I = V/R = 12/4.
State Kirchhoff’s current law (KCL).The algebraic sum of currents at a node is zero; equivalently, total current entering equals total current leaving.
State Kirchhoff’s voltage law (KVL).The algebraic sum of voltage rises and drops around any closed loop is zero.
What is the equivalent resistance of 2 Ω and 3 Ω resistors in series?5 Ω; series resistances add.
What is the equivalent resistance of 6 Ω and 3 Ω resistors in parallel?2 Ω, because 1/R = 1/6 + 1/3 = 1/2.
An unloaded divider has 2 kΩ above and 4 kΩ below across 12 V. What is the voltage across the 4 kΩ resistor?8 V: 12 × 4/(2 + 4). The output is across the lower resistor.
A 12 V source delivers 2 A to a load. How much power does the load absorb?24 W, using P = VI for the load’s voltage and current.
Under the passive sign convention, when is p = vi positive?When current enters the element’s terminal marked positive for voltage; the element is absorbing power.
Find the time constant for R = 10 kΩ and C = 100 μF in a first-order RC circuit.τ = RC = 10,000 × 100 × 10⁻⁶ = 1 s.
After a long time on DC, how does an ideal capacitor behave in steady state?As an open circuit; its voltage is constant, so i = C dv/dt = 0.
After a long time on DC, how does an ideal inductor behave in steady state?As a short circuit; its current is constant, so v = L di/dt = 0.
Write the current-voltage relationship for an ideal capacitor using the passive sign convention.i = C dv/dt, where current enters the terminal at the positive reference voltage.
Write the voltage-current relationship for an ideal inductor using the passive sign convention.v = L di/dt, where voltage is measured positive at the terminal into which the reference current enters.
A sinusoidal voltage has a peak value of 10 V. What is its RMS value?10/√2 ≈ 7.07 V, for a sinusoid.
Find the inductive reactance of a 0.1 H inductor at 50 Hz.Xₗ = 2πfL = 2π × 50 × 0.1 ≈ 31.4 Ω.
Find the capacitive reactance of a 10 μF capacitor at 1 kHz.X꜀ = 1/(2πfC) ≈ 15.9 Ω.
What is the series-resonant frequency for L = 10 mH and C = 10 μF?f₀ = 1/(2π√LC) ≈ 503 Hz.
How do you find the Thevenin equivalent resistance at a pair of terminals?Deactivate independent sources and find the resistance looking into the terminals: replace ideal voltage sources with shorts and ideal current sources with opens.
An 18-card electrical circuits deck, with the first card ready to grade and the remaining questions queued for review.

That is a MySummaries deck, filled with electrical circuits material. Yours is written from your own notes. Start free

Work the cards, not just the formula names

For the first seven cards, practise translating the circuit description into a relationship before calculating. KCL and KVL are conservation rules: charge does not accumulate indefinitely at an ideal node, and energy balances around a closed loop. Resistor combinations and dividers then test whether you can identify the topology. Do not use the series formula for parallel resistors, or assume a divider gives the stated output when a load is connected. The 8 V divider answer assumes an unloaded output; a connected load can change the lower-leg resistance and the voltage.

The power card needs one more check in a full circuit problem: identify which voltage and current belong to the same element, and use a consistent sign convention. A negative value under the passive sign convention means the element is delivering power, not absorbing it. Include units in calculated answers and keep sensible significant figures.

The component cards test the steady-state assumptions behind common shortcuts. An ideal capacitor is open and an ideal inductor is a short only after DC steady state has been reached. During a transient, capacitor voltage and inductor current cannot change instantaneously in an ideal model. The differential relationships on the deck explain why: a sudden voltage change across a capacitor would require an unbounded current, and a sudden current change through an inductor would require an unbounded voltage.

For the AC cards, use frequency in hertz and capacitance in farads before substituting. Reactance is measured in ohms. Inductive reactance increases with frequency; capacitive reactance decreases with frequency. The RMS conversion shown here applies to a sinusoid, not every possible waveform. At series resonance, the ideal LC resonance formula gives the frequency at which the inductive and capacitive reactances have equal magnitude. A practical circuit’s response can also depend on resistance and how the circuit is connected.

The Thevenin card is a verbal procedure, so make your answer operational: remove the load, deactivate independent sources, then calculate resistance looking into the load terminals. A dependent source is not turned off; if one is present, use an appropriate test source to find the resistance. That condition is a common omission in otherwise sound explanations.

A concise core list helps you decide which facts must come back immediately during problem solving. Use it after the deck: try to state each item from memory, then check the values and conditions.

Here is the Must not miss core behind the deck:

Must not miss coreElectrical Circuits
KCL: algebraic current sum at a node is zero; KVL: algebraic voltage sum around a closed loop is zero.
Resistors: series Rₑq = ΣR; parallel 1/Rₑq = Σ(1/R). An unloaded divider gives Vout = Vin × Rlower/(Rupper + Rlower).
Ideal components at DC steady state: capacitor open, inductor short; transient laws are iC = C dvC/dt and vL = L diL/dt.
Sinusoidal AC: Vrms = Vpeak/√2; Xₗ = 2πfL; X꜀ = 1/(2πfC); ideal series resonance f₀ = 1/(2π√LC).
The four circuit relationships and conditions to retrieve before attempting longer calculations.

Use missed marks to choose the next review

A wrong answer is useful only if you identify what failed. Was it a forgotten relationship, a unit conversion, a mistaken topology, or an omitted condition such as “unloaded” or “at DC steady state”? After grading a card Again or Hard, say the corrected answer once and solve a small variation: change one resistor, frequency or component value and recalculate. This checks whether you understand the method rather than memorising the number on the card.

Keep missed items specific. “Revise AC” is too broad to act on; “I inverted the capacitor reactance formula” tells you what to retrieve next time. A remediation card can turn a repeated error into a direct question:

Remediation tray

You lost this mark twice: when finding Thevenin resistance with a dependent source present, which sources do you deactivate, and what do you use to find the resistance?

Add cardDismiss

Review due cards before adding more facts. When the core relationships are reliable, use worked circuit problems to practise combining them—for example, reduce a resistor network, find a divider voltage, and then calculate the load current. Return to the deck after that practice and grade each answer honestly. Flashcards are most useful here as a short retrieval routine that exposes gaps; the calculations show whether you can apply the retrieved fact.

How MySummaries helps

Build an Electrical Circuits revision board from your own PDFs, slides or handwritten notes, then generate and review cards from its sections. You can keep the formulas and conditions together with your source material and revisit cards as they come due. Explore MySummaries.