NCEA 91526: electrical systems (Level 3 Physics)

What NCEA 91526 assesses

NZQA's standard limits the exam to a selection from four areas:

• Resistors in DC circuits: internal resistance and simple use of Kirchhoff's laws.
• Capacitors in DC circuits: the parallel plate capacitor, capacitance, dielectrics, series and parallel capacitors, charge, voltage and current against time, the time constant and stored energy.
• Inductors in DC circuits: magnetic flux and flux density, Faraday's and Lenz's laws, voltage and current against time, the time constant, self inductance, stored energy and the transformer.
• AC circuits: energy dissipation in a resistor with DC and AC, peak and rms values, phase in LR and CR series circuits, phasor diagrams, reactance, impedance and resonance in LCR circuits.

Achieved shows awareness of how simple facets of phenomena relate to a situation. Merit gives explanations for the phenomena, concepts or principles. Excellence connects concepts or principles that relate to the situation.

The NCEA 91526 exam in 2026 and 2027

NCEA 91526 is one of three Level 3 Physics externals, with 91523 and 91524. The 2026 exam is on Thursday 12 November, in the afternoon session. NZQA's 2027 timetable is not out yet: it says exams run from 9 November to 3 December 2027. The 2026 and 2027 specifications match: you need an approved calculator, a ruler and a protractor, the 2025 exam came with a resource booklet (L3-PHYSR), and you may need to show mathematically that two principles are connected. Give units and sensible significant figures.

How NCEA 91526 is marked: grade score marking

Each question scores N0 to E8 and the three add to 24. Reading a time constant earns a, relating rms to heating earns m, and explaining why a transformer needs changing flux earns e.

NCEA 91526 cut scores

These are NZQA's cut scores for the total out of 24, taken from each year's assessment schedule. Over these five years Achieved needed 7 or 8, Merit 14 or 15, and Excellence 19 or 20. The 2026 cut scores will appear in NZQA's 2026 schedule once the exam has been marked.

Worked examples at each grade

Achieved: charging a capacitor

A 220 µF capacitor charges through a 4.7 kΩ resistor from a 12 V supply. The time constant is:

After one time constant the capacitor voltage has reached 63% of the supply: 12 × (1 − e⁻¹) = 7.6 V.

Merit: peak and rms, and what AC heating means

A heater of resistance 115 Ω runs from a 230 V rms supply. The peak voltage is √2 times the rms voltage, not 230 under a square root:

Merit explains what this means: 230 V rms heats the resistor at the same average rate as 230 V DC would. The power in the heater is not steady, because it follows the square of the voltage, and its maximum is 325² ÷ 115 = 920 W, twice the average.

Excellence: a transformer and why DC fails

A transformer has 1000 turns on the primary and 50 on the secondary, with 230 V rms across the primary. The secondary voltage is 230 × 50 ÷ 1000 = 11.5 V. It feeds a 2.3 Ω load:

An ideal transformer would need 57.5 ÷ 230 = 0.25 A, so the extra 0.022 A is the price of the 8% lost to heating in the coils and core. Excellence connects the ideas: the secondary voltage is induced by a changing magnetic flux (Faraday's law, ε = −N ΔΦ ÷ Δt), so a steady DC supply, which gives a constant flux, induces no emf and the transformer does nothing. Lenz's law supplies the sign: the induced emf opposes the change that makes it.

Check your thinking with a question on the page:

Exam answers

The answers and a worked mark scheme come with today's paper once it is marked. We do not publish official or past paper answers. Every question on the daily paper is our own.

Use the daily paper as a practice exam

Uni-Sine publishes a free daily paper on the NCEA Level 3 Physics track. It is a short timed paper of 8 questions worth 25 to 35 marks, not a full NCEA exam, and it is not written by NZQA. Its topics include capacitors and electromagnetic induction, which cover the capacitor and inductor parts of 91526, and electric fields. It does not list AC circuits or phasors, so practise those from your class notes. See the NCEA Level 3 Physics guide for the whole subject.

Common mistakes in NCEA 91526

NZQA's 2025 report on the Level 3 Physics exams says, for 91526:

• Mixing up inductors and capacitors. Many candidates also misjudged what a capacitor does in a parallel circuit when a switch is open or closed.
• "Current follows the path of least resistance". The report calls this a significant misconception. Current splits among all the branches.
• Emf only in induction. Many candidates could not discuss emf outside electromagnetic induction.
• Peak voltage from rms. Many put the whole rms value under the square root. Only the factor is √2.

Read next

New Zealand · NCEA Level 3NCEA Level 3 Physics: standards, exam date and practiceNCEA Level 3 Physics explained: wave, mechanical and electrical systems externals, the internals, the 2026 exam date, 2027 dates and worked examples.