Light continuous spectrum

If we pass white light through a vapor composed of the atoms of an element, we see its absorption spectrum, a series of dark lines on an otherwise continuous spectrum (Fig 1.11). The absorption lines have the same frequencies as the lines in the emission spectrum and suggest that an atom can absorb radiation only of those same frequencies. Absorption spectra are used by astronomers to identify elements in the outer layers of stars. 

To identify a certain pigment, monochromatic light is required, but the assessment of food quality by a human inspector or by a device requires normal daylight. The evaluation procedure, however, to be discussed in the next section, also involves decomposition into monochromatic (red, green, and blue) regions. Monochromatic dissection of a continuous spectrum by monochromators can be achieved in three ways ... 

With the room lights darkened, view the light using the Flinn C-Spectra . The top spectrum viewed will be a continuous spectrum of the white lightbulb. The bottom spectrum will be the absorption spectrum of the red solution. The black areas of the absorption spectrum represent the colors absorbed by the red food coloring in the solution. Use colored pencils to make a drawing in the data table of the absorption spectra you observed. 

There was a more significant problem, however. Rutherford s atomic model seemed to contradict the laws of nineteenth-century physics. According to these assumptions, an electron in motion around a central body must continuously give off radiation. Consequently, one should be able to observe a continuous spectrum (a rainbow ) of light energy as the electron gives off its radiation. 

When white light (such as the light from an ordinary light bulb) is passed through a prism, a rainbow effect is seen. This is known as a continuous spectrum and includes all the colours in the visible part of the electromagnetic spectrum (from about 400 to 700 nm). 

Ives et al. (79) tended to reject our hypothesis that brown colours of mixed oxides (and in particular less pure NdaOs) are due to traces of praseodymium. However, these authors noted the interesting effect that such dark colours (also of Pro,oaTho.9802) bleach in the reflection spectrum at higher T. It was noted that mantles of NdaOa alone rapidly hydrate to a pinkish powder (carbonate ) in humid air. It is weU-known that -type sesquioxides are far more reactive, and for instance dissolve almost instantaneously in aqueous acid, than cubic C-type samples. Ives et al. 19) also studied the broad continuous spectrum of the orange light emitted from Thi- 11 0 2+2/ where the oxidation state of uranium is rather uncertain. 

The room was made dark and when a hot glass tube had cooled until it was just barely visible, a fragment of iodine was thrown into the tube, which thereupon filled with luminous vapours. To obtain more brilliancy one heats the vapour of iodine in a Bohemian glass tube by means of an enameller s lamp. The contents of the tube look like a red-hot bar of iron. One may also volatilize iodine around a platinum spiral brought to a vivid incandescence the luminous vapour rises like a real flame about the spiral. It is a case of farm without combustion. The light from the iodine gives a continuous spectrum, or rather a confused primary spectrum one perceives traces of characteristic channellings but no lines of the secondary spectrum. 

Light emitted from a black body solely as a result of high temperature as in electric bulb is known as incandescence or thermal radiation. The quality and quantity of thermal radiation is a function of temperature only. The wavelength of most strongly emitted radiation in the continuous spectrum from black body is given by Wien s Displacement Law-, Amax T —h. (where h is Wien s constant = 2.898 X 10 3 m deg). 

Purchase some rainbow" glasses from a nature, toy, or hobby store. The lenses of these glasses are diffraction gratings. Looking through them, you will see lig ht separated into its color components. Certain light sources, such as the moon or a car s headlights, are separated into a continuous spectrum—in other words, all the colors of the rainbow appear in a continuous sequence from red to violet. 

An electron not restricted to particular energy levels would release light continuously as it spiraled closer into the nucleus. A broad spectrum of colors would be observed rather than the distinct lines. 

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