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    The study workshop · Level 2

    One step. One circuit.

    Electrical revision at your pace. Five questions, clear working and space to try again. Allow 15–20 minutes.

    Quick recap — open before you practise

    1. Convert, then rearrange

    1 A = 1,000 mA. Start with V = I × R. Divide both sides by I to get R = V ÷ I.

    Example: 12 V ÷ 0.5 A = 24 Ω.

    2. Follow the paths

    Series: same current; add resistances. Parallel: same voltage across each branch.

    Two 10 Ω resistors: 20 Ω in series, 5 Ω in parallel.

    3. Protection has conditions

    An MCB rating alone cannot tell you its operating time. Use the actual current and the specific device’s time–current curve.

    Schneider Electric: breaker characteristics

    Source checked 26 September 2026.

    Fresh mixed sets rotate through all seven topics. Starting fresh clears this set. Answers stay in this session only.

    Question 1 of 5 · Resistivity

    Find conductor length

    A copper conductor has CSA 4 mm² and resistance 0.43 Ω. Find its length. Use copper ρ = 1.72 × 10⁻⁸ Ω·m = 0.0172 Ω·mm²/m. Assume constant temperature.

    Use the unit menu or type a unit, such as 500 mA. A typed unit takes priority. Equivalent units and sensible rounding are accepted.

    Ideal resistor circuits for study. Protection questions practise concepts; permitted disconnection times require the relevant circuit, earthing arrangement and current course guidance.