Word Finder - spectrum

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A range; a continuous, infinite, one-dimensional set, possibly bounded by extremes.

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Specifically, a range of colours representing light (electromagnetic radiation) of contiguous frequencies; hence electromagnetic spectrum, visible spectrum, ultraviolet spectrum, etc.

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The autism spectrum.

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The pattern of absorption or emission of radiation produced by a substance when subjected to energy (radiation, heat, electricity, etc.).

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The set of eigenvalues of a matrix.

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Of a bounded linear operator A, the set of scalar values λ such that the operator A—λI, where I denotes the identity operator, does not have a bounded inverse; intended as a generalisation of the linear algebra sense.

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(abstract algebra) The set, denoted Spec(R), of all prime ideals of a given ring R, commonly augmented with a Zariski topology and considered as a topological space.

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Specter, apparition.

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The image of something seen that persists after the eyes are closed.

Our eyes are capable of seeing only a narrow spectrum of light.

Let AoBo be a plane wave-surface of the light before it falls upon the prisms, AB the corresponding wave-surface for a particular part of the spectrum after the light has passed the prisms, or after it has passed the eye-piece of the observing telescope.

The combined effect of the two is to produce a spectrum sloping up from left to right.

Julius to explain the "flash spectrum" seen during a solar eclipse at the moment at which totality occurs..

He wrote numerous papers on photometry and spectrum analysis in Poggendorff's Annalen and Berichte der k.

The spectrum of helium has been very carefully studied by Runge and Paschen.

Spectrum analysis thus passed quickly out of the stage in which its main purpose was " analysis " and became our most delicate and powerful method of investigating molecular properties; the old name being no longer appropriate, we now speak of the science of " Spectroscopy."

At present we have still to content ourselves with a much diminished intensity of light when working with gratings, but there is some hope that the efforts to concentrate the light into one spectrum will soon be successful.

The resolving power in the case of gratings is simply mn, where m is the order of spectrum used, and n the total number of lines ruled on the grating.

Opticians should supply sufficient information of the dispersive properties of their materials to allow dµ/dX to be calculated easily for different parts of the spectrum.

If a thickwalled capillary tube is passed over the platinum tube and its length so adjusted that the liquid rises in it by capillary action just above the level of the tube, the spectrum may be examined directly, and the loss of light due to the passage through the partially wetted surface of the walls of the tube is avoided.

In consequence the question as to the connexion of the spectrum with the temperature of the gas seems to the present writer to lose some of its force.

When now a small bead of a salt of sodium or lithium is placed in the flame the spectrum of the white hot platinum is traversed by the dark absorption of the D lines.

The efforts which were consequently made in the early days of spectroscopy to discover some numerical relationship between the different wave lengths of the lines belonging to the same spectrum rather disregard the fact that even in acoustics the relationship of integer numbers holds only in special and very simple cases.

Balmer, who showed that the four hydrogen lines in the visible part of the spectrum may be represented by the equation n = A(i - 4/s2), where n is the reciprocal of the wave-length and therefore proportional to the wave frequency, and s successively takes the values 3, 4, 5, 6.

The most complete hydrogen spectrum is that measured by Evershed 8 in the flash spectrum observed during a total solar eclipse, and contains thirty-one lines, all of which agree with considerable accuracy with the formula, if the frequency number n is calculated correctly by reducing the wave-length to vacuo.9 It is a characteristic of Balmer's formula that the frequency approaches a definite limit as s is increased, and it was soon discovered that in several other spectra besides hydrogen, series of lines could be found, which gradually come nearer and nearer to each other as they become fainter, and approach a definite limit.

In the case of other metallic groups similar series have also been found, but while in the case of the alkali group nearly the whole spectrum is represented by the combined set of three series, such is not the case with other metals.

All its lines arrange themselves in two families of series, in other words, the spectrum looks like that of the superposition of two spectra similar to those presented by the alkali metals.

Before leaving the subject, we return for a moment to the spectrum of hydrogen.

Kayser on examining the spectrum recognized the fact that the two series were related to each other like the two branch series, and this was subsequently confirmed.

If we compare Balmer's formula with the general equation of Ritz, we find that the two can be made to agree if the ordinary hydrogen spectrum is that of the side branch series and the constants a', b, c and d are all put equal to zero.'

It seems remarkable, however, that we should not have succeeded yet in reproducing in the laboratory the trunk and main branch of the hydrogen spectrum, if the spectra in question really belong to hydrogen.

According to this view the different lines are given out by different molecules, and we should have to take averages over a number of molecules to obtain the complete spectrum just as we now take averages of energy to obtain the temperature.

King, that in the case of the so-called spectrum of cyanogen these tails can be observed.

When we compare together electric discharges the intensity of which is altered by varying, the capacity, we are unable to form an opinion as to whether the effects observed are due to changes in the density of the luminous material or changes of temperature, but the experiments of Sir William and Lady Huggins 1 with the spectrum of calcium are significant in suggesting that it is really the density which is also the determining factor in cases where different concentrations and different spark discharges produce a change in the relative intensities of different lines.

These lines in the case of the spark cannot be due entirely to the increased mass of vapour near the poles, but indicate a real change of spectrum probably connected with a higher temperature.

The method adopted consisted in photographing the spectrum on a film which was kept in rapid motion by being attached to the front of a rotating disk.

Bunsen first announced their discovery, for according to their view every combination of an element showed the characteristic spectrum of its constituent atoms; it did not matter according to this view whether a salt,' e.g.

The experiment proves only the transparency of the gases experimented upon, and this is confirmed by the fact that bodies like bromine and iodine give on heating an emission spectrum corresponding to the absorption spectrum seen at ordinary temperatures.

In many cases there is a considerable difficulty in deciding whether a particular spectrum belongs to a compound body or to one of the elements composing the compound.

There is a vast amount of literature on the subject, but in spite of the difficulty of conceiving a luminous carbon vapour at the temperature of an ordinary carbon flame, the evidence seems to show that no other element is necessary for its production as it is found in the spectrum of pure carbon tetrachloride and certainly in cases where chlorine is excluded.

Another much disputed spectrum is that giving the bands which appear in the electric arc; it is most frequently ascribed to cyanogen, but occasionally also to carbon vapour.

Compounds generally show spectra of resolvable bands, and if an elementary body shows a spectrum of the same type we are probably justified in assuming it to be due to a complex molecule.

These bands appear in the solar spectrum as we observe it, but are due to absorption by the oxygen contained in the atmosphere.

Under different conditions we obtain (a) a continuous spectrum most intense in the yellow and green, (b) the spectrum dividing itself into two families of series, (c) a spectrum of lines which appears when a strong spark passes through oxygen at atmospheric pressure, (d) a spectrum of bands seen in the kathode glow.

Stark discovered that in the case of the series spectrum of hydrogen and of other similar spectra the lines were displaced indicating high velocities; in other cases no displacements could be observed.

No conclusion can therefore be drawn, as Stark' has more recently pointed out, respecting the charge of the molecule which emits the observed spectrum.

As the atomic weight of the haloid increases the spectrum is displaced towards the red.

The most typical case in this respect is the effect of a solvent on the absorption spectrum of a solution.

The chromates of sodium, potassium and ammonium, as well as the bichromates of potassium and ammonium, were found to give the same absorption spectrum.

Nor is the effect of these chromates confined to the blocking out simply of one end of the spectrum, as in the visible part, but two distinct absorption bands are seen, which seem unchanged in position if one of the above-mentioned chromates is replaced by another.

Besides the blue and purple of the spectrum he was able to recognize only one colour, yellow, or, as he says in his paper, "that part of the image which others call red appears to me little more than a shade or defect of light; after that the orange, yellow and green seem one colour which descends pretty uniformly from an intense to a rare yellow, making what I should call different shades of yellow."

This slit is set in such a position as to transmit a single line of the spectrum, e.g.

In the case of narrower lines, however, higher dispersion is required to prevent the light of the continuous spectrum on either side of the dark line from blotting out the monochromatic image.

This forms an image of the solar spectrum in its focal plane on the camera slit (1).

On the spectrum see Spectroscopy.

Certain absorption bands at the blue end of the spectrum are supposed to be due to rare elements such as samarium.

The spectrum, also, is very characteristic. The atomic weight, 226.4, places the element in a vacant position in group II.

Its wave-length is probably very near 55'71 tenth-metres, and it is very close to, if not absolutely coincident with, a prominent line in the spectrum of krypton.

By an ingenious method devised by Engelmann, it may be shown that the greatest liberation of oxygen, and consequently the greatest assimilation of carbon, occurs in that region of the spectrum represented by the absorption bands.