Hydrogen's line spectrum
"Hydrogen's line spectrum" is a free, interactive Class 12 Physics simulation for NEET and JEE, built on the lesson "Line spectra of hydrogen" in Atoms. Pick the starting and final levels. The strip below shows where each possible line falls; yours is the bold one. Only whole-number levels exist, so only certain gaps, and only certain lines. hν = Ei − Ef = 13.6(1/nf² − 1/ni²) eV, and an atom absorbs exactly the lines it can emit. JEE Main asked 33 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
From the lesson Line spectra of hydrogen in Atoms. Change the values and watch what happens.
In JEE Main
42 shifts analysed
33 questions from Atoms across the 42 JEE Main shifts Lumi has analysed (2017–2026).
The idea behind it
NCERT §12.5
- A transition from a higher level ni to a lower level nf (nf < ni) sends out a photon of frequency νif with hνif = Eni − Enf (Eq. 12.11).
- Both ni and nf are whole numbers, so only certain energy differences, and so only certain discrete frequencies, are possible: this is the line spectrum.
- Emission lines come from electrons dropping from higher to lower states. Absorption happens when an atom takes in a photon whose energy exactly matches the gap to a higher state.
- Light with a continuous range of frequencies passed through a rarefied gas therefore comes out with dark absorption lines at the frequencies the atoms absorbed.
- For hydrogen, hν = 13.6 eV (1/nf² − 1/ni²). Using hc ≈ 1240 eV nm: 2 → 1 gives 10.2 eV (about 122 nm, ultraviolet); 3 → 1 gives 12.09 eV (about 103 nm); 3 → 2 gives 1.89 eV (about 656 nm, red).
- Bohr's explanation of the hydrogen spectrum was a major achievement that drove the development of quantum theory, and he received the Nobel Prize in Physics in 1922.
Questions
3 answers
- What does the "Hydrogen's line spectrum" simulation show?
- Pick the starting and final levels. The strip below shows where each possible line falls; yours is the bold one.
- Does JEE Main ask questions from Atoms?
- Yes. JEE Main asked 33 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
- Is this simulation free?
- Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Line spectra of hydrogen" in Atoms (Class 12 Physics).
Embed this simulation
Free, with a link back
Teaching this idea? Put the simulation on your own page or LMS with this code.