Question detail

A transformer is used in a primary-secondary coil comparison pole-test 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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Topic

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

Question

A transformer is used in a primary-secondary coil comparison pole-test 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: fluxcue603a coilcue603b fieldcue603c polecue603d gridcue603e motorcue603f generatorcue603g transformercue603h compasscue603i currentcue603j voltagecue603k forcecue603l.

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 fluxcue603a coilcue603b fieldcue603c polecue603d gridcue603e motorcue603f generatorcue603g transformercue603h compasscue603i currentcue603j voltagecue603k forcecue603l: 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 Uses of the generator effect (HT only), then explain how it links to a bar magnet and plotting compass practical and the objective to state that the generator effect is used in a dynamo to generate direct current.

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