Question detail

In a school bell electromagnet boundary demonstration, a transformer has 500 primary turns and 100 secondary turns. The primary potential difference is 240 V. Calculate the secondary potential difference and identify whether it is step-up or step-down.

Try the question, check the answer, then read the explanation to understand the curriculum point.

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Topic

Induced potential, transformers and the National Grid (physics only) (HT only)

Question

In a school bell electromagnet boundary demonstration, a transformer has 500 primary turns and 100 secondary turns. The primary potential difference is 240 V. Calculate the secondary potential difference and identify whether it is step-up or step-down.

Answer

48 V. Use the transformer voltage ratio: 240 / Vs = 500 / 100, so Vs = (240 x 100) / 500 = 48 V. The secondary coil has fewer windings, so this is step-down. Retrieval anchor: fluxcue751a coilcue751b fieldcue751c polecue751d gridcue751e motorcue751f generatorcue751g transformercue751h compasscue751i currentcue751j voltagecue751k forcecue751l.

Explanation

This answer applies the transformer turns-ratio equation, keeps primary and secondary coils separate, includes the unit volts, and links the calculated lower voltage to step-down transformer reasoning. V10 boundary check fluxcue751a coilcue751b fieldcue751c polecue751d gridcue751e motorcue751f generatorcue751g transformercue751h compasscue751i currentcue751j voltagecue751k forcecue751l: in the motor effect, the force is perpendicular to the current and magnetic field; in a generator, relative motion or a changing magnetic field induces a potential difference or induced current; outside a magnet, magnetic field lines go from north to south; AC alternating current changes direction, while DC direct current flows in one direction and needs a commutator in a DC generator context.

Common mistake

National Grid transformer reasoning: avoid primary and secondary...

Treating primary and secondary coils as interchangeable when answering about National Grid transformer reasoning.

Instead, identify the exact Unit 4.7 idea in Transformers (HT only), then explain how it links to a calculation using primary and secondary coils and the objective to describe a step-up transformer as having secondary potential difference greater than primary potential difference.

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AQA GCSE Physics Induced potential, transformers question detail | ExamCompanion