The electric or magnetic lines of force in a region.

1. In soldering, welding, and brazing, a material applied to the pieces to be united to reduce the melting point of solders and filler metals and to prevent the formation of oxides.

2. A substance used to promote the fusing of minerals or metals.

3. Additive for plastics composition to improve flow during physical processing.

4. In enamel work, a substance composed of silicates and other materials that forms a colorless, transparent glass when fired. Also know as fondant.

The product of the number of particles per unit volume and their average velocity; a special case of the physics definition. Also known as flux density.

1. The integral over a given surface of the component of a vector field (for example, the magnetic flux density, electric displacement, or gravitational field) perpendicular to the surface; by definition, it is proportional to the number of lines of force crossing the surface.

2. The amount of some quantity flowing across a given area (often a unit area perpendicular to the flow) per unit time; the quantity may be, for example, mass or volume of fluid, electromagnetic energy, or number of particles.