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    Hi, can anyone help with this question about the text below:

    "Explain, with the aid of a diagram, what is meant by sharp 'lines' in the second paragraph of the passage."

    Here is the passage:

    "'In the last few years, because of the growing demand for high-precision measurement, it has become desirable to have some more fundamental standard of time than any that can be derived from astronomical observation. One such standard is the natural period of characteristic electromagnetic waves produced by a vibrating atom or molecule. These electro magnetic waves, due to particular modes of vibration, are of very precise frequency and form sharp 'lines' in the spectrum. Optical spectral lines are unsuitable for use as a standard of time because we have no means of measuring the frequencies directly."


    My understanding of sharp lines is the sharp lines of light given off that gives an element it's 'light signature' but I don't think that is what it means as it states 'Optical spectral lines are unsuitable for use as a standard of time because we have no means of measuring the frequencies directly'

    Thanks for reading!
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    I think it's trying to say that atomic clocks work by counting oscillations in the radio/microwave portion of the electromagnetic spectrum
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    (Original post by danielcb12)
    Hi, can anyone help with this question about the text below:

    "Explain, with the aid of a diagram, what is meant by sharp 'lines' in the second paragraph of the passage."

    Here is the passage:

    "'In the last few years, because of the growing demand for high-precision measurement, it has become desirable to have some more fundamental standard of time than any that can be derived from astronomical observation. One such standard is the natural period of characteristic electromagnetic waves produced by a vibrating atom or molecule. These electro magnetic waves, due to particular modes of vibration, are of very precise frequency and form sharp 'lines' in the spectrum. Optical spectral lines are unsuitable for use as a standard of time because we have no means of measuring the frequencies directly."


    My understanding of sharp lines is the sharp lines of light given off that gives an element it's 'light signature' but I don't think that is what it means as it states 'Optical spectral lines are unsuitable for use as a standard of time because we have no means of measuring the frequencies directly'

    Thanks for reading!
    My guess is that they want you to demonstrate knowledge of electron energy level transitions, which absorb/emit (depending on whether the electron is moving up or down an energy level) at very precise frequencies.

    If you compare the passage with this article:

    https://en.wikipedia.org/wiki/Atomic...Optical_clocks

    the passage seems to be saying

    1) we used to measure time by astronomical observations;
    2) now we use atomic clocks (as Joined up says, at microwave frequencies); and
    3) it would be better to able to use optical frequencies but we cannot measure those frequencies directly.

    The Wiki article suggests that problem (3) has been solved, at least in the lab - see para 6.3.
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    (Original post by Holmstock)
    My guess is that they want you to demonstrate knowledge of electron energy level transitions, which absorb/emit (depending on whether the electron is moving up or down an energy level) at very precise frequencies.

    If you compare the passage with this article:

    https://en.wikipedia.org/wiki/Atomic...Optical_clocks

    the passage seems to be saying

    1) we used to measure time by astronomical observations;
    2) now we use atomic clocks (as Joined up says, at microwave frequencies); and
    3) it would be better to able to use optical frequencies but we cannot measure those frequencies directly.

    The Wiki article suggests that problem (3) has been solved, at least in the lab - see para 6.3.
    Thanks for the response, I think I get it now...
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    "electromagnetic waves produced by a vibrating atom or molecule"

    It says that it is the frequency given off from the vibration of the atom, is this the same as electron energy level transitions?
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    (Original post by danielcb12)
    "electromagnetic waves produced by a vibrating atom or molecule"

    It says that it is the frequency given off from the vibration of the atom, is this the same as electron energy level transitions?
    well it is an electron energy transition, but it's a change in spin rather than the change between shells that I guess you've already looked at.

    hope this explains it http://hyperphysics.phy-astr.gsu.edu.../acloc.html#c4
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    (Original post by Joinedup)
    well it is an electron energy transition, but it's a change in spin rather than the change between shells that I guess you've already looked at.

    hope this explains it http://hyperphysics.phy-astr.gsu.edu.../acloc.html#c4
    That's really helpful, thank you!
 
 
 
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