A transformer steps down a given voltage Isom 220V to 55V. If current in primary coil is 4mA, then current in secondary coil will be:
Correct answer: A. 16mA
- A. 16mA
- B. 2mA
- C. 8mA
- D. 4mA
Explanation
When a transformer steps down the voltage, it increases the current. In this case, since the voltage is stepped down from 220V to 55V, and the current in the primary coil is 4mA, the current in the secondary coil will be increased by a factor of 220/55, which is 4. Therefore, the current in the secondary coil will be 4mA * 4, which is 16mA.
This question appeared on the KMU Centralized Admission Test 2020 paper, which you can sit online with every answer explained.
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About Transformers
Transformers transfer alternating electrical energy between coils by mutual induction, with voltage ratio determined by the turns ratio. The topic covers step-up and step-down transformers, current changes, ideal power conservation and practical losses such as heating and flux leakage. A transformer requires changing magnetic flux, so it does not operate with steady direct current.
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