voltmetri

Voltmetri, or voltmeter, is an instrument used to measure the electric potential difference between two points in an electrical circuit. To avoid loading the circuit, a voltmeter is connected in parallel with the element under test and is designed with a high input impedance, typically from kilohms to megohms. Measurements may be of direct current (DC) or alternating current (AC), and instruments range from simple analog meters to digital multimeters that display a numeric value.

Analog voltmeters use either a moving-coil galvanometer for DC voltages or a moving-iron mechanism for AC voltages; digital voltmeters convert the input with an analog-to-digital converter and show a digital readout. Some digital models provide true RMS measurements, which respond to the effective value of non-sinusoidal signals, while others display an average-responding value corrected for sine waves. Instruments are offered with different voltage ranges and may auto-range.

Accuracy and calibration: practical voltmeters offer varying accuracy, from about 0.01% to several percent of full-scale, depending on design, range, and temperature. Calibration is typically traceable to national or international standards; regular calibration ensures reliable readings.

Applications and safety: voltmeters are essential in laboratory electronics, maintenance, and field work for verifying supply voltages, diagnosing circuits, and checking power quality. When measuring high voltages, proper insulation, isolation, and correct range selection are critical to user safety and instrument protection.

History: the term voltmeter derives from the name of Alessandro Volta; the device emerged in the late 19th century as electrical measurement techniques evolved. See also multimeter, oscilloscope, electrical measurement standards.