Electromagnetic flowmeter​ is a kind of variable area flowmeter. The working principle of electromagnetic flowmeter is that in a vertical cone tube that expands from bottom to top, the gravity of the circular cross-section float is borne by hydrodynamic force, and the float can move in the cone.

The English name of flowmeter is flowmeter, which is defined by the national science and technology terminology Approval Committee as an instrument indicating the measured flow and / or the total amount of fluid within the selected time interval.