Which tool is most commonly used for checking electrical circuits?

The multimeter is the most commonly used tool for checking electrical circuits because it is designed to measure a variety of electrical parameters such as voltage, current, and resistance. This versatility makes it indispensable for troubleshooting and diagnosing issues within electrical systems. When a technician needs to determine whether there is an electrical flow, to check the voltage across a component, or to measure the resistance of a circuit, the multimeter provides the necessary capability to perform all these tasks efficiently.

In contrast, a torque wrench is primarily used for applying a specific amount of torque to fasteners, such as bolts and nuts, rather than for electrical measurements. A micrometer and a caliper are tools used for precise measurement of physical dimensions and are not suitable for electrical circuit testing. Therefore, the multimeter stands out as the essential tool for anyone working with or diagnosing electrical circuits.