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![[Post New]](/templates/default/images/icon_minipost_new.gif) 2 Mar 2008 18:00:35 IST
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A question given in FIITJEE's Open Test on Feb 10th reads..........
Q.Column - 1 represents different materials at high temperature.Column 2 represent type of emission spectrum produced by them.
Column - 1 Column - 2
A.Sodium p.Continuous spectra
B.Mercuric oxide q.Band spectra
C.Tungsten r.Line spectra
D.Platinum Black s.Band spectra superimposed
over continuous spectra
Recently I have come across some questions of these type..........the problem is although they are giving the key to such problems ,they are not mentioning anywhere how the answer comes...............please explain me how to solve such type of problems explaining the solution to above one............
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"Nenenthedhavano naake teleedu"
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2 Mar 2008 18:07:58 IST
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Molecules give band spectra
Atoms give line spectra
I think platinum black gives continuous spectra (black body)
woh superimposed i dun knw
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2 Mar 2008 19:45:28 IST
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Harsha, read this theory
The spectrum formed from white light contains all colors, or frequencies, and is known as a continuous spectrum.
Continuous spectra are produced by all incandescent solids and liquids and by gases under high pressure.
A gas under low pressure does not produce a continuous spectrum but instead produces a line spectrum, i.e., one composed of individual lines at specific frequencies characteristic of the gas, rather than a continuous band of all frequencies.
If the gas is made incandescent by heat or an electric discharge, the resulting spectrum is a bright-line, or emission, spectrum, consisting of a series of bright lines against a dark background.
A dark-line, or absorption, spectrum is the reverse of a bright-line spectrum; it is produced when white light containing all frequencies passes through a gas not hot enough to be incandescent.
It consists of a series of dark lines superimposed on a continuous spectrum, each line corresponding to a frequency where a bright line would appear if the gas were incandescent.
The Fraunhofer lines appearing in the spectrum of the sun are an example of a dark-line spectrum; they are caused by the absorption of certain frequencies of light by the cooler, outer layers of the solar atmosphere.
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God has given you one face, and you
make yourself another.
~William Shakespeare
You were born an original. Don't die a copy.
~John Mason |
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2 Mar 2008 22:04:39 IST
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i m sorry i was busy .. Na is going to show line spectra (lines obtained at 589nm and 589.9nm) that is also called as atomic spectra. HgO is compound so it w'll show band spectra. band spectra is shown by compound and molecules. W wire is used for making the filament of bulb used in spectrometers and it gv white light (act as black body). so that spectrum is continious one... i m searching fr proper explanation of pt black spectra as soon as i'll get i'll expalin u...
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3 Mar 2008 14:37:52 IST
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But Sir for Mercuric oxide the answer given is both Band spectra and Line spectra.
And for Platinum Black it is continuous spectra.
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4 Mar 2008 00:03:44 IST
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hmm yea becoz Hgo dissociate on heating to gv Hg and O2
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