We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
454 RICHARDSON'S BLUEBOOK OF PROJECTION
emission in the case of an incandescent metal is readily explained. The molecules of every substance are at all times in a state of agitation. Increased temperature increases this agitation. Collisions between molecules occur. During some of these collisions negatrons become detached from their atoms. Often the attraction of the positive ion draws back the lost negatron to its source. But where the velocity of the motion of the negatron is relatively great, it may continue moving away from the atom until it has passed through the surface of the material and continued some distance out into the space beyond. The greater the agitation of the molecules, that is, the higher the temperature of the metal, the more frequently will negatrons be detached from their atoms with sufficient initial velocity to enable them to leave the material and enter into the surrounding air or vacuum.
Thus the action of incandescence in promoting increased emission is known because the nature of increased temperature in a metal is known. Increased temperature in a metal is simply increased agitation of the molecules. When this agitation becomes sufficiently great, both light and negatrons are emitted from the metal, whicK is then said to be incandescent.
But the fundamental nature of light itself is still a matter of conflicting theories, and until more is known about it the nature of electronic emission from photoelectric substances will not be wholly understood. All that can be said at this time is that when light falls upon a photo-electric metal, emission of negatrons from its surface is very greatly increased. The effect varies with the color of the light. It is also dependent upon the thickness of the emitting substance. In modern photoelectric cells the layer of emitting material is only one or two molecules thick, or less than one-billionth of an inch. (11) But why light has this effect upon certain metals is still far from clear.