Which of the following is not a basic component of eddy current equipment?

In eddy current testing, the fundamental components of the equipment include the amplifier, coil, and detector. The amplifier enhances the electrical signals generated by the eddy currents induced in the material being tested, allowing for easier interpretation of results. The coil serves as the tool that generates the electromagnetic field and detects changes in the material's electrical properties due to the presence of flaws or variations. The detector then processes these signals to provide data regarding the integrity of the tested material.

Liquid couplants are not a basic component of eddy current equipment because this testing method typically does not require a medium to be introduced between the probe and the test surface as some other techniques do, such as ultrasonic testing. Eddy current testing relies on the electromagnetic fields which do not necessitate a couplant for effective operation. This distinction underscores the unique feature of eddy current testing in comparison to other non-destructive testing methods.