When the output circuit of a transformer is open, no current flows through the output coil, leading to the primary experiencing only the magnetizing and leakage inductance. This prevents large currents from flowing through the input, avoiding wire damage despite the absence of back EMF. As impedance is added to the secondary, it reflects back to the primary, appearing in parallel with the primary's magnetizing inductance. The discussion also hints at a quiz question regarding the transformed secondary impedance in relation to the turns ratio of the coils. Understanding these principles is crucial for comprehending transformer behavior under open-circuit conditions.
