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.
JUST HOW CLEVER ARE YOU ? What’s Wrong With This Circuit?
During the coming fifteen days write to the editor and tell him what is wrong with this circuit. There will be a series of five of these puzzle circuits. The projectionist who sends in highest percentage of correct answers will receive an award well worth the effort. Those who do not win the award will gain a knowledge of the various circuits which will be valuable to them, perhaps more valuable than a prize. Write in your answer now.
two pinholes. Others have used prisms, lenses, and mirrors to get the effect. They use monochromatic light, say a yellow sodium flame and get regular bands of yellow and black.
The strange thing is that we see interference phenomena practically every day and don’t know it. The bright colors we see in a film of oil are due to interference of the light reflected from the back surface of the film with light reflected from the front surface. Here we have light of all wavelengths, so the bands of the same width, but overlap causing the rainbow effect. Soap bubbles and cracks in glass get their color the same way.
It would seem we ought to be able to get interference from any two sources of sodium light. Actually we find that we must use the same source for both interfering waves. The explanation is that the phase of light is constantly changing, and no two different sources keep in phase. However we must have light from two sources, so we split the beam of light
T e u ty -eight
we have, and by reflection or refraction bring the two parts together again to interfere.
It may be of interest to know that there are practical applications of interference phenomena. The interference caused by reflection from the two sides of a thin film of air between two glass plates, shows the accuracy of the surface planes. Where there are considerable irregularities there are many narrow crooked bands. When both surfaces are accurate planes there will be uniform illumination or darkness or wide bands.
Newton’s rings are seen when a lens of a long radius of curvature placed on a flat piece of glass is illuminated. There is a large spot in the center which is surrounded by rings of different colors whose radii are dependent on the thickness of the air film between lens and plate.
Interference fringes are also used to test the parallelism of the two sides of plates of glass.
(To Be Continued).