Transformers Rely on Electromagnetic Induction

Steps:

• Recall that transformers transfer electrical energy between circuits using mutual induction.
• Identify the core principle: a changing magnetic field from the primary coil induces emf in the secondary coil via Faraday's law.
• Evaluate each option against this principle to find the accurate statement.
• Confirm A matches the induction process, while others misrepresent materials or function.

Why A is correct:

• Faraday's law states that a changing magnetic flux induces emf in a coil, which occurs in the secondary due to the alternating current in the primary.

Why the others are wrong:

• B: Iron is used for its high magnetic permeability to enhance flux linkage, not electrical conductivity.
• C: Transformers step up/down AC voltage but do not convert AC to DC; rectification is needed for that.
• D: Transformers require AC input and do not convert DC to AC.

Final answer: A