What measuring instrument is used to check resistance on the direct ground stud?

The correct measuring instrument for checking resistance on the direct ground stud is the ohmmeter. An ohmmeter measures the resistance in ohms within a circuit or across a component. When assessing a ground stud, it's essential to determine the integrity and effectiveness of the grounding connection. Low resistance values indicate a good ground connection, while high resistance levels could suggest issues such as corroded connections or poor bonding.

Using an ohmmeter allows the mechanic to ensure there is a solid electrical connection, which is crucial for safety and functionality in aerospace applications. In contrast, other instruments, such as voltmeters and ammeters, are designed for measuring voltage and current, respectively, not resistance. Similarly, calipers are used for measuring physical dimensions and are not suitable for electrical measurements.