What effect occurs when a supply is initially connected to a load made up of coils, such as transformers?

• A. The current spikes up for a fraction of a second
• B. The current remains constant
• C. The current decreases to zero
• D. The voltage collapses

Answer: (A)

When you first connect a supply to a coil or transformer, the current doesn’t immediately settle to its normal operating value. Coils store energy in their magnetic field, and they resist sudden changes in current. At the moment of energization, the magnetic field is just starting to form, and the circuit can momentarily draw a much larger current than usual—the inrush current. This transient surge lasts only a fraction of a second as the magnetic field builds and the inductive effects settle, after which the current settles toward its steady-state value. That brief spike is the observable effect when inductive loads are connected.