What is the formula used to calculate the impedance of an eddy current test coil?

The formula used to calculate the impedance of an eddy current test coil is derived from the relationship between the inductive reactance, resistance, and overall impedance in an AC circuit. Impedance represents the total opposition that a circuit presents to alternating current and is expressed in complex form, which incorporates both resistance and reactance.

The correct formula is Z = √(XL^2 + R^2). This equation reflects that the total impedance is the square root of the sum of the squares of the inductive reactance (XL) and the resistance (R). The use of squares in this context is crucial because both reactance and resistance contribute to the overall impedance, but they are orthogonal (meaning they operate at 90-degree phase angles relative to each other).

Inductive reactance (XL) is caused by the coil's inductance and is frequency-dependent, while resistance (R) is the inherent opposition to the current due to the material properties of the coil. By combining these two components in this way, we accurately model how they interact in an AC system, providing a true representation of the eddy current test coil's behavior.

The other options do not correctly describe the relationship necessary to compute impedance. For example, the formula Z =