Atoms & Nuclei

JEE Main level, single correct, medium

70 of 239

Question 70 of 239

The electron in a hydrogen atom first jumps from the third excited state to the second excited state and subsequently to the first excited state. The ratio of the respective wavelengths λ1λ2\dfrac{{\lambda }_{1}}{{\lambda }_{2}} of the photons emitted in this process is:

Show answer and solution

Answer: (B) 207\dfrac{20}{7}

1λ1=R(132−142)=R×7144\dfrac{1}{{\lambda }_{1}}=R\left(\dfrac{1}{{3}^{2}}-\dfrac{1}{{4}^{2}}\right)=\dfrac{R\times 7}{144}
1λ2=R(122−132)=R×536\dfrac{1}{{\lambda }_{2}}=R\left(\dfrac{1}{{2}^{2}}-\dfrac{1}{{3}^{2}}\right)=\dfrac{R\times 5}{36}
⇒λ1λ2=R×536×144R×7=207\Rightarrow \dfrac{{\lambda }_{1}}{{\lambda }_{2}}=\dfrac{R\times 5}{36}\times \dfrac{144}{R\times 7}=\dfrac{20}{7}

JEE Main question paper PDF

Open a shift to read the full paper on this page, or download it.

JEE Main 2025 Apr 2 Shift 1 question paper

Open Download PDF

Opening paper…

Explain it as a whiteboard videoStep-by-step, in Hinglish or English. Your first video needs no login.Solved it on paper but got it wrong?Upload a photo of your working. Mistake Doctor marks the exact line that broke.
See it move: Atoms: Rutherford, Bohr and X-rays simulationDrag the sliders and watch the numbers in this question change.Revise Modern Physics firstFormula sheet, solved examples and the traps students fall into.

More Physics practice

JEE Main Physics practice question on Atoms & Nuclei (Bohr's Atomic Model), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.