Special Features:

Measures low-frequency magnetic fields; elf (extrememly low-frequency) meter

Properties:

An instrument which measures the rate of regularly recurring variations in an electric current or voltage and is usually calibrated in hertz (cycles per second or cps). The value may be expressed by means of a pointer and calibrated dial vibrating reed or a digital read out display. For instruments which measure radio frequencies, see calibrator, frequency; and wavementer. excludes: counter electronic digital.