Question

Two series of spectral lines of atomic hydrogen which do not belong to infrared spectral region are

• A. Lyman and Paschen
• B. Balmer and Brackett
• C. Pfund and Lyman
• D. Lyman and Balmer

Answer 1

Answer: (D)

Series of spectral lines
1. Lyman series $\left(n^{\prime }=1\right)$
- The series is named after its discoverer Theodore Lyman.
- Lyman series lies in the ultraviolet region.
2. Balmer formula $\left(n^{\prime }=2\right)$
- The series is named after its discoverer Johann Balmer.
- It is technically visible part of the spectrum with wavelength longer than $400nm$ and shorter than $700nm$.
3. Paschen series $\left(n^{\prime }=3\right)$
- Named after the German physicist- Friedrich Paschen
- The paschen lines all lie in the infrared band.
4. Brackett series $\left(n^{\prime }=4\right)$
- Named after the American physicist Frederick Sumner Brackett.
- The spectral lines of Brackett series lie infrared band.
5. Pfund series $\left(n^{\prime }=5\right)$
- Discovered by August Herman Pfund.
- Lie in infrared region.
6. Humphreys series $\left(n^{\prime }=6\right)$
- American physicist Curtis J. Humphreys.
- The spectral lines of Humphreys series lie in infrared region.