A transformer is used to change theI. resistanceII. capacitanceIII. currentIV. voltage
Correct answer: D. III or IV.
- A. I and II.
- B. I and IV.
- C. II and III.
- D. III or IV.
Explanation
A transformer is an electrical device used to transfer electrical energy between two or more circuits through electromagnetic induction. It primarily functions to change the voltage levels - either stepping up (increasing) or stepping down (decreasing) the voltage, which in turn affects the current due to the power conservation principle (Power = Voltage × Current). Therefore, transformers are used to change the current and voltage levels in a circuit.Option A: 'I and II' is incorrect because transformers do not change resistance (I) or capacitance (II).Option B: 'I and IV' is incorrect because while transformers change voltage (IV), they do not change resistance (I).Option C: 'II and III' is incorrect because transformers do not change capacitance (II) though they do affect current (III).Option D: 'III or IV' is correct because transformers are designed to change both current (III) and voltage (IV) depending on how they are configured.
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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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