Abstract
For measurement of liquid density, the following two methods are usually adopted.
(1) To measure the apparent mass of solid with known mass m and density p, suspended in liquid.
(2) To use hydrometer.
In either method, the effect of surface tension of liquid is unavoidable.
A method reported in this paper is based on a new idea. A float with a permanent magnet is put in the liquid and another magnet (permanent magnet or electro magnet) is placed outside the liquid to suspend the float by magnetic repulsion. Theoretically, the apparent increase of mass of the outside magnet is equal to the apparent mass of the float in the liquid. This principle was proved through experiments, too.
This method is considered to be applicable to the continuous measurement of density of liquid flow in a pipeline.
