What is the term used for the total opposition to the flow of current in a transformer?

The total opposition to the flow of current in a transformer is referred to as impedance. Impedance is a comprehensive measure that combines both resistance and reactance, encompassing the effects of both the resistive elements of the circuit and the reactive elements that arise due to inductance and capacitance.

In a transformer, the reactance plays a significant role due to the alternating nature of the current and the magnetic fields involved. Therefore, impedance becomes critical in assessing how much the transformer will oppose the flow of alternating current. It is measured in ohms (Ω) and is essential for evaluating the performance and efficiency of electrical systems.

Resistance refers specifically to the opposition to current flow in a conductor, without considering reactive components, making it a narrower term compared to impedance. Conductance, on the other hand, is the reciprocal of resistance and represents how easily electricity flows, but does not address the influence of reactance. Voltage drop indicates the reduction in voltage in a circuit and is not a measure of opposition to current flow but rather a consequence of it.

Given these definitions, impedance accurately describes the total opposition encountered in a transformer when dealing with alternating current, which is why it is the correct choice in this context.