Question detail
A transformer is used in a National Grid substation energy-transfer 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 National Grid substation energy-transfer 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: fluxcue372a coilcue372b fieldcue372c polecue372d gridcue372e motorcue372f generatorcue372g transformercue372h compasscue372i currentcue372j voltagecue372k forcecue372l.
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 fluxcue372a coilcue372b fieldcue372c polecue372d gridcue372e motorcue372f generatorcue372g transformercue372h compasscue372i currentcue372j voltagecue372k forcecue372l: 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 Electromagnetism, then explain how it links to a current-carrying wire between magnetic poles and the objective to interpret diagrams of electromagnetic devices in order to explain how they work.
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