Observing Spectral Lines: The Highest Order & Color Sequence

In summary, assuming a spectrometer reading of Hydrogen produced two strong spectral lines at 656.3nm and 410.1nm, and a diffraction grating with 500 lines/mm, the highest order of spectrum that can be fully observed is 3 for the 656.3nm line and 4 for the 410.1nm line. The sequence of line colours observed when the physicist begins with the spectrometer telescope at a deviation angle of zero and rotates it through 90 degrees is violet, red, violet, violet, red, violet, red.
  • #1
elevenb
35
1

Homework Statement



In a question I was asked, assuming a spectrometer reading of Hydrogen produced two strong spectral lines at 656.3nm and 410.1nm. And also assuming the diffraction grating had 500 lines/mm

What is the highest order of spectrum which can be fully observed , i.e value of m.

and assuming the physicist begins with the spectrometer telescope eyepiece at a deviation angle of zero and rotates it through 90 degrees, determine the sequence of line colours that she sees?

Homework Equations



mλ=dsinθ

The Attempt at a Solution

I worked out that the highest value of m for the 656.3nm line is 3 and for the 410.1nm line it's four but because it says fully observed I said three because the two lines can be observed fully at this order of spectrum.

For the second part I wrote out multiples of the wavelengths, I got

410.1, 820.2, 1230.3, 1640.4

656.3, 1312.6, 1968.9

So if I call the 410.1nm one violet, and the 656.3nm one red. Are the colours she sees

Violet, red, violet, violet, red, violet, red?
 
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  • #2
mc94 said:

Homework Statement



In a question I was asked, assuming a spectrometer reading of Hydrogen produced two strong spectral lines at 656.3nm and 410.1nm. And also assuming the diffraction grating had 500 lines/mm

What is the highest order of spectrum which can be fully observed , i.e value of m.

and assuming the physicist begins with the spectrometer telescope eyepiece at a deviation angle of zero and rotates it through 90 degrees, determine the sequence of line colours that she sees?

Homework Equations



mλ=dsinθ

The Attempt at a Solution

I worked out that the highest value of m for the 656.3nm line is 3 and for the 410.1nm line it's four but because it says fully observed I said three because the two lines can be observed fully at this order of spectrum.

For the second part I wrote out multiples of the wavelengths, I got

410.1, 820.2, 1230.3, 1640.4

656.3, 1312.6, 1968.9

So if I call the 410.1nm one violet, and the 656.3nm one red. Are the colours she sees

Violet, red, violet, violet, red, violet, red?

The result is correct, but the physicist observes angles. It does not change the order as the sine function is monotonously increases with your multiples of wavelengths.

ehild
 

FAQ: Observing Spectral Lines: The Highest Order & Color Sequence

1. What are spectral lines?

Spectral lines are narrow bands of light that are produced when atoms or molecules emit or absorb energy. They appear as distinct lines of color in a spectrum and can be used to identify the chemical elements present in a substance.

2. How are spectral lines observed?

Spectral lines are observed using a spectroscope, which separates light into its component wavelengths. The spectroscope produces a spectrum, which is a range of colors or wavelengths that can be analyzed to determine the presence and characteristics of spectral lines.

3. What is the highest order of spectral lines?

The highest order of spectral lines is the Balmer series, which consists of the visible lines in the hydrogen spectrum. These lines are named after Johann Balmer, who first discovered and studied them in the 19th century.

4. What is the color sequence of spectral lines?

The color sequence of spectral lines follows the order of the visible light spectrum, from red to violet. This is due to the fact that each color corresponds to a specific wavelength of light, and the spectral lines are created when atoms or molecules absorb or emit specific wavelengths.

5. How are spectral lines used in scientific research?

Spectral lines are used in a variety of scientific research fields, including astronomy, chemistry, and physics. They can be used to identify the chemical composition of stars, study the behavior of atoms and molecules, and provide insight into the structure and properties of matter. Spectral lines are also used in practical applications such as medical imaging and environmental monitoring.

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