UFLA/2003
Inglês > Adjectives > Agreement

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A variety of experiments can be performed to illustrate the nature of light, but perhaps the most well known is the classic "double slit experiment" first performed by Thomas Young in 1803. In the first part of the experiment, a light is shone through a tiny vertical slit in a screen and allowed to pass on to a second detecting screen. The light spreads out after passing through the hole, and a large illuminated area that fades into darkness at the edges shows up on the detecting screen. To form this pattern, the light actually bends or diffracts when passing through the slit. In the second part of the experiment, light is shone through two paralels slits. This time the light passes through the slits, but instead of creating a large lighted area, the detecting screen now shows alternating bands of light and darkness. The band in the center is the brightest. Around that are alternating bands of light and darkness with the light bands becoming less intense the farther away they are from the central one. What is happening is called the "phenomenon of interference". The waves of light from the two slits interfere with £each other. Like all waves, light waves have crests, their highest points, and throughs, their lowest points. In places where the crests coming from one slit extend over the crests coming from the other slit, the result is an intensification of light, and light bands appear on the detecting screen. In places where the crests from one slit overlap the throughs from the other slit, they cancel each other out, and the result is an area of darkness on the detecting screen. But what happens if particles of light, or photons, are shot one after the other through the slits? If only one slit is open, these photons build up the same pattern as that of the beam of light. The fascinating thing is that if two slits are open and photons are fired one at a time through either of them the pattern that builds up on the detecting screen is the same pattern obtained when a beam of light is shone through two slits. In other words, a single photon appears to "know" whether one slit or two are open. (Gear, Jolene & Gear, Robert - Cambridge Preparation for the TOEFL Test - 2002 - Cambridge University Press - UK) Look at the phrase EACH OTHER in the passage (ref. 2). Choose the one best alternative that EACH OTHER refers to: