What does a voltage tester measure?

A voltage tester is specifically designed to measure the voltage level in volts within an electrical circuit. This instrument allows technicians and electricians to determine whether a circuit is live and to check the potential difference between two points. Knowing the voltage is crucial for troubleshooting electrical systems, ensuring safety, and verifying that electrical devices are operating correctly.

The other options refer to different measurements relevant in electrical work: current flow in amps pertains to the flow of electricity, resistance in ohms relates to how much a material opposes the flow of electric current, and energy consumption in watts measures the total power being used by devices. However, a voltage tester does not measure these aspects, reinforcing the importance of understanding the scope and function of specific electrical measurement tools.