voltmetro

Voltmetro is a measuring instrument used to determine the electrical potential difference between two points, commonly expressed in volts. It is one of the basic tools for electrical measurement, designed to present voltage with minimal disturbance to the circuit under test by exhibiting a relatively high input impedance.

There are two main families of voltmetros: analog and digital. Analog voltmetros rely on a moving-coil or moving-iron mechanism in which a current proportional to the voltage drives a pointer on a scale. Digital voltmetros use analog-to-digital conversion and display a numerical value, often with true RMS capability for AC measurements. Digital models typically offer higher input impedance and broader functionality, such as auto-ranging and data logging.

Electrical connection is in parallel with the element whose voltage is to be measured. For DC measurements, polarity matters, and the meter is connected with the correct polarity. For AC measurements, many voltmetros report the RMS value. The burden voltage, or the voltage drop across the meter itself, can affect sensitive circuits, particularly in low-voltage applications.

Common specifications include measurement range, input impedance, accuracy, resolution, and response time. Handheld voltmetros (often part of a digital multimeter) commonly cover several hundred volts in DC and AC ranges, with input impedances around 10 megaohms. High-voltage voltmetros are designed with appropriate insulation and safety features for kilovolt measurements.

History traces the development from early galvanometers to modern digital instruments. Voltmetros are essential in electronics laboratories, power systems, automotive diagnostics, and field service, where reliable voltage readings underpin testing and troubleshooting.