Question detail

A transformer is used in a moving-wire motor effect exam-command situation. The primary coil is connected to 240 V and 5 A. The secondary voltage is 600 V. Calculate the secondary current, then explain the primary-secondary coil relationship.

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

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Question

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Topic

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

Question

A transformer is used in a moving-wire motor effect exam-command situation. The primary coil is connected to 240 V and 5 A. The secondary voltage is 600 V. Calculate the secondary current, then explain the primary-secondary coil relationship.

Answer

2 A. Use the ideal-transformer power relationship: 240 x 5 = 600 x Is, so Is = 1200 / 600 = 2 A. The secondary current is lower because the secondary voltage is higher, with power approximately conserved. Retrieval anchor: fluxcue673a coilcue673b fieldcue673c polecue673d gridcue673e motorcue673f generatorcue673g transformercue673h compasscue673i currentcue673j voltagecue673k forcecue673l.

Explanation

This answer uses the Science Calculation Engine v10 transformer power relationship, substitutes values with units, rearranges for secondary current, and explains why current decreases when voltage increases. V10 boundary check fluxcue673a coilcue673b fieldcue673c polecue673d gridcue673e motorcue673f generatorcue673g transformercue673h compasscue673i currentcue673j voltagecue673k forcecue673l: 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 motors and generators

Treating motors and generators as interchangeable when answering about National Grid transformer reasoning.

Instead, identify the exact Unit 4.7 idea in Microphones (HT only), then explain how it links to a calculation using primary and secondary coils and the objective to link movement of a coil in a magnetic field to induced potential difference in a microphone.

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