An unidentified gas X when heated, is found to radiate light of wavelengths 423 nm, 520 nm, and 640 nm. In another situation, after white light was passed through a cooled sample of gas X, certain wavelengths were found missing. The missing wavelengths could be -
An unidentified gas X when heated, is found to radiate light of wavelengths 423 nm, 520 nm, and 640 nm. In another situation, after white light was passed through a cooled sample of gas X, certain wavelengths were found missing. The missing wavelengths could be -
The correct options are
B 423 nm
D 640 nm
When a gas radiates upon heating, typically, we find the radiation to consist of a discrete set of lines - called the emission spectrum. Also, when white light is passed through the same gas in a cooler temperature, we find that the light that comes out has a few missing wavelengths - the absorption spectrum.
Interestingly, they exactly correspond to each other - the missing lines in the absorption spectrum are literally the emission spectral lines, like the negative of a photographic film (I'll not be surprised if some of you don't know what the negative of a photo film is - ask your parents for some 90's wisdom!).
Look at the spectra of hydrogen gas to know what I mean. Both spectra have lines at exactly the same wavelengths (dark lines - absorption spectrum; bright lines - emission spectrum), as shown.
B
423 nm
D
640 nm
When a gas radiates upon heating, typically, we find the radiation to consist of a discrete set of lines - called the emission spectrum. Also, when white light is passed through the same gas in a cooler temperature, we find that the light that comes out has a few missing wavelengths - the absorption spectrum.
Interestingly, they exactly correspond to each other - the missing lines in the absorption spectrum are literally the emission spectral lines, like the negative of a photographic film (I'll not be surprised if some of you don't know what the negative of a photo film is - ask your parents for some 90's wisdom!).
Look at the spectra of hydrogen gas to know what I mean. Both spectra have lines at exactly the same wavelengths (dark lines - absorption spectrum; bright lines - emission spectrum), as shown.
