Which device is used to measure electrical resistance?

The device specifically designed to measure electrical resistance is the ohmmeter. This instrument operates by passing a known current through the resistor being tested and measuring the voltage drop across it. By applying Ohm's Law (V=IR), it can calculate the resistance value in ohms.

In contrast, a voltmeter is used to measure voltage, an ammeter measures current, and a wattmeter measures electrical power. Each of these devices serves a distinct purpose related to different electrical parameters, but only the ohmmeter is tailored for assessing resistance. This specialization makes the ohmmeter the correct choice for the question about measuring electrical resistance.