What causes a voltage to appear across the secondary winding of a transformer when an AC voltage source is connected across its primary winding?
Capacitive coupling
Displacement current coupling
Mutual inductance✓Bonne réponse
Mutual capacitance
Explication
AC in the primary sets up a changing magnetic field in the core, and that changing field links the secondary turns and induces a voltage in them. The coupling is magnetic, so the capacitive choices are wrong.