What instrument is used to measure the rate of flow of an electric current?

The milliampere meter is a specific instrument designed to measure the flow of electric current, particularly in milliamperes. This is particularly important in the field of esthetics, where low levels of current are often used for various treatments, such as microcurrent therapy. The milliampere meter provides precise readings of small currents, making it ideal for monitoring and ensuring safety during cosmetic procedures that employ electrical devices.

Other instruments, although related to electricity, serve different purposes. A voltmeter measures the electric potential difference (voltage) across two points, which does not directly indicate current flow. A wattmeter measures power in watts, which is a product of voltage and current but does not provide a direct measurement of current flow itself. An ohmmeter is used to measure resistance in an electrical circuit, which again does not relate directly to the measurement of current. Thus, the milliampere meter is the correct choice for measuring the rate of flow of an electric current.