Coloured light

The visible light having the shortest wavelength is violet in colour. Light having an even shorter wavelength is therefore more than or beyond violet which, from Latin, is ultraviolet. 

Today, scientists explain the northern lights as resulting from streams of protons and electrons—plasma—emanating from the Sun. When the electrons from the plasma interact with gaseous atoms in Earth s upper atmosphere, the atoms emit coloured light. 

Body colour Light yellow-green Yellow-green... 

Triboluminescence is the phenomenon that is observed when coloured light is emitted on grinding, crushing or fracturing certain crystalline compounds, e.g. the bluish white light emitted from sugar. This phenomenon has been known for over 300 years but has remained a curiosity without an obvious application, until very recently when Sage postnlated that this effect could be used to detect flaws in composite materials. ... 

The name pyrotechnic is derived from the Greek words pyr (fire) and techne (an art), which describes the effect observed from a burning pyrotechnic composition. These effects include the production of coloured smoke, noise, and the emission of bright-coloured light. Pyrotech-... 

Table 8.8 Examples of pyrotechnic compositions which emit white and coloured light...

If the tar oils are accompanied by small quantities of mineral oils, the latter may dissolve in the aromatic nitro-derivatives and so settle to the bottom of the vessel. In such case the deposited layer is separated and distilled in a small flask, only the first portions of the distillate, containing the bulk of the light mineral oils, being collected. This is treated with zinc and hydrochloric acid (cooling somewhat) to reduce the nitro-com-pounds, and diluted with water the amines formed dissolve in the water as hydrochlorides and the mineral oils separate as slightly coloured light drops. 

In the presence of anions which are precipitated by calcium chloride solution, proceed as follows. Precipitate the acetic acid test solution with calcium chloride solution, and collect the precipitate on a filter or in a centrifuge tube. Remove the water from the precipitate either by drying or by washing with alcohol and ether. Mix a small amount of the precipitate with diphenylamine in a dry micro test-tube, add a little concentrated phosphoric acid, and heat gently over a free flame. Calcium phosphate and free oxalic acid are formed, and the latter condenses with the diphenylamine to aniline blue and colours the hot phosphoric acid blue. The colour disappears on cooling. Dissolve the melt in alcohol, when a blue colouration appears. Pour the alcoholic solution into water thus precipitating the excess of diphenylamine, which is coloured light blue by the adsorption of the dyestuff. The dye may be extracted from aqueous solution by ether. 

Partial seizures are bursts of abnormal activity in a localized area of the brain and cause symptoms such as repetitive contractions of a single group of muscles or abnormal sensation, such as hearing voices or seeing coloured lights, and abnormal behaviour. 

Incident plane polarised light after traversing the polariser is absorbed by the dichroic dye, whose transition moment is parallel to the electric vector of the light. The internal reflector reflects the coloured light back through the polariser. Thus, the non-addressed background appears coloured. 

RECLiNDis (v). James Grieve X BX 44/18 cross ripening mid-September, yield medium to high, early-bearing fruit medium size, spherical, bright red colour (lightly mottled) fruit juicy, delicately firm-fleshed. 

Coloured Light attenuation (an algal problem). Classification must distinguish toxic effects from reduced growth due to light attenuation. 

Figure 9. The residues identified by the Evolutionary Trace (ET) method on the external face of the receptor. In each orientation the helix/helices in focus are coloured mid grey while the ET residues in focus are coloured light grey. The remaining residues are dark grey, a) helices 5 and 6, b) helix 4, c) helices 2 and 3 d) helix7.

The flame of an alcohol lamp looks almost colourless. Vhen a length of platinum v/ire which is dipped into a metal salt solutioh is put into the flame, the flame is coloured in the upper part by the wire. The colour is peculiar to the kind of the metal strontium colours the flame red, sodium yellow, barium pale green and copper blue. This is applied to the qualitative analysis of metal ions as the colour flame test. The emission of the coloured light is caused by atomic metal gas or a gas consisting of molecules of metal compound, and the process may be set out as follows ... 

Potassium chlorate in composition gives a high temperature flame which is enough to excite molecules to emit coloured light. Moreover it contains chlorine atoms which are effective to deepen the colour of the flame i.e. it can produce the colour creating molecules, SrCl, CuCl, BaCl etc. in the flame. 

The purpose of these compositions is to produce a flower in coloured lights or flames. There are two kinds generally used one is the low temperature class(a flame temperature 1700-2200 C) and the other is the high temperature class(a flame temperature 2500-3000 C), where the compositions contain magnesium. 

Multiple choice determination device Eive electronically controlled coloured light pulses (yellow, red, green, blue, white) are activated in alternating sequences. Pressing a button with the same colour indicates that the test person has recognized and registered the colour both instantly and correctly. This device has proved to be a useful instrument in clinical testing environments. (14)... 

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