Which of the following tools is used to test for voltage?

A voltmeter is specifically designed to measure voltage in an electrical circuit. It provides a direct reading of the electrical potential difference between two points, allowing linemen to quickly determine if an electrical circuit is live and the voltage level present. This is crucial for ensuring the safety of electrical work and for diagnosing potential issues in circuits.

While other tools like a clamp meter and multimeter can also measure voltage, the voltmeter is dedicated to this purpose alone, making it the most straightforward tool for testing voltage. A clamp meter primarily measures current and may provide voltage readings as an added feature, and a multimeter can measure voltage as well, but it serves multiple functions beyond just voltage reading. Therefore, the voltmeter stands out as the instrument specifically tailored for testing voltage.