Question detail
A transformer is used in a overhead cable transmission field-shape 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.
At a glance
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Topic
The motor effect
Question
A transformer is used in a overhead cable transmission field-shape 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: fluxcue407a coilcue407b fieldcue407c polecue407d gridcue407e motorcue407f generatorcue407g transformercue407h compasscue407i currentcue407j voltagecue407k forcecue407l.
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 fluxcue407a coilcue407b fieldcue407c polecue407d gridcue407e motorcue407f generatorcue407g transformercue407h compasscue407i currentcue407j voltagecue407k forcecue407l: 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
motor-effect force direction: avoid motors and generators
Treating motors and generators as interchangeable when answering about motor-effect force direction.
Instead, identify the exact Unit 4.7 idea in Fleming's left-hand rule (HT only), then explain how it links to a step-up transformer on the National Grid and the objective to recall the factors that affect the size of the force on a current-carrying conductor.
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