Fluoroscope. An apparatus for making examinations by means of the X-rays.
Fluoroscopic Screen. A screen overspread with fluorescent material and employed for fluoroscopic examinations in connection with the X-rays.
Force. Any change in the condition of matter with respect to motion or rest. Force is measured by the acceleration or change of motion that it can impart to a body of a unit mass in a unit of time. For instance, ten pounds pressure of steam will be indicated on a gauge made for measuring steam. That pressure of steam, with the proper volume behind it, is capable of instantly producing a given part of a horse-power. In the same way ten volts of electro-motive force is capable of pushing a current so as to exert a certain fraction of horse-power.
Force, Electro-magnetic. The force of attraction or repulsion exerted by the electro-magnet. It is also known as electric force in the electro-magnetic system.
Foucault Currents. (See [Currents, Foucault].)
Fractional Distillation. The process of evaporating liquids by heat, the most volatile being the first treated. When that has been evaporated and distilled the heat is raised and the next most volatile liquid is evaporated, and so on until all are evaporated, leaving as a residue the solids that were a part of the original mass of liquid.
Friction. The effect of rubbing, or the resistance which a moving body encounters when in contact with another body.
Frictional Electric Machine. An apparatus for the development or generation of high-tension frictional electricity.
Frictional Electricity. Electricity produced by the friction of dissimilar substances.
Full Load. A complete load. The greatest load a machine or secondary battery will carry permanently. The full capacity of a motor running at its registered speed for its horse-power.