Which instrument would be used to accurately gauge the resistance of a wire?

The appropriate instrument for accurately gauging the resistance of a wire is an ohmmeter. An ohmmeter measures electrical resistance directly, providing a reading in ohms. It functions by passing a small, known current through the wire and measuring the voltage drop across it. According to Ohm's Law (V = IR), where voltage (V) is the product of current (I) and resistance (R), the ohmmeter can calculate the resistance based on these two variables.

Other instruments listed have different specific functions: a micrometer is used for measuring small lengths with high precision, typically in mechanical applications; an oscilloscope is designed for displaying voltage over time, helping analyze waveform characteristics in signals; and a wattmeter measures electrical power in watts, focusing on the product of voltage and current, rather than resistance. Thus, the ohmmeter is uniquely suited for the task of measuring electrical resistance accurately.