Verified Solution • 2025–26 Session moderate

QPages 384-386: Q27: HC Verma: Concepts of Physics - Volume 2 Bohr's Model and Physics of the Atom Pages 384-386: Q27 Solution: A beam of light having wavelengths distributed uniformly…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students often incorrectly assume that hydrogen gas at room temperature only absorbs Lyman series photons (transitions from $n=1$), leading them to conclude no visible light is absorbed. You must recognize that the Balmer series ($n=2 \to n>2$) falls within the visible spectrum and that a non-negligible fraction of hydrogen atoms are thermally excited to the $n=2$ state, allowing absorption of the 486 nm photon.

A beam of light having wavelengths distributed uniformly between 450 nm to 550 nm passes through a sample of hydrogen gas. Which wavelength will have the least intensity in the transmitted beam?

Step-by-Step Verified Solution

**Answer:** Wavelength = 486 nm will have least intensity. **Step-by-Step Explanation:** The light has wavelengths 450�550 nm. Hydrogen gas at room temperature has electrons in n = 1. Absorption occurs when photon energy matches a transition from n = 1. The Lyman series lines are at 121.6 nm, 102.6 nm, etc., all in UV. So no absorption occurs in the 450�550 nm range. Wait�the question says least intensity in transmitted beam," which implies absorption. The Balmer series lines are at 656 nm, 486 nm, 434 nm, etc. 486 nm n=4_2) falls in the 450�550 nm range. So this wavelength will be absorbed, reducing intensity.

All Questions in this Chapter

QPage 383: Q1 QPage 383: Q2 QPage 383: Q3 QPage 383: Q4 QPage 383: Q5 QPage 383: Q6 QPage 383: Q7 QPage 383: Q8 QPage 383: Q9 QPage 383: Q10 QPage 383: Q11 QPage 383: Q12 QPage 383: Q13 QPages 382-383: Q1 QPages 382-383: Q2 QPages 382-383: Q3 QPages 382-383: Q4 QPages 382-383: Q5 QPages 382-383: Q6 QPages 382-383: Q7 QPages 382-383: Q8 QPages 382-383: Q9 QPages 382-383: Q10 QPages 383-384: Q1 QPages 383-384: Q2 QPages 383-384: Q3 QPages 383-384: Q4 QPages 383-384: Q5 QPages 383-384: Q6 QPages 384-386: Q1 QPages 384-386: Q2 QPages 384-386: Q3 QPages 384-386: Q4 QPages 384-386: Q5 QPages 384-386: Q6 QPages 384-386: Q7 QPages 384-386: Q8 QPages 384-386: Q9 QPages 384-386: Q10 QPages 384-386: Q11 QPages 384-386: Q12 QPages 384-386: Q13 QPages 384-386: Q14 QPages 384-386: Q15 QPages 384-386: Q16 QPages 384-386: Q17 QPages 384-386: Q18 QPages 384-386: Q19 QPages 384-386: Q20 QPages 384-386: Q21 QPages 384-386: Q22 QPages 384-386: Q23 QPages 384-386: Q24 QPages 384-386: Q25 QPages 384-386: Q26 QPages 384-386: Q27 QPages 384-386: Q28 QPages 384-386: Q29 QPages 384-386: Q30 QPages 384-386: Q31 QPages 384-386: Q32 QPages 384-386: Q33 QPages 384-386: Q34 QPages 384-386: Q35 QPages 384-386: Q36 QPages 384-386: Q37 QPages 384-386: Q38 QPages 384-386: Q39 QPages 384-386: Q40 QPages 384-386: Q41 QPages 384-386: Q42 QPages 384-386: Q43 QPages 384-386: Q44 QPages 384-386: Q45 QPages 384-386: Q46

Related Learning Resources & Exam Preparation

Chapter Practice Bank
Practice all topic-wise questions from Bohr's Model and Physics of the Atom
Reference Textbook Solutions
Explore complete chapter exercises for HC Verma: Concepts of Physics - Volume 2
Competitive PYQ Question Bank
Browse year-wise authentic previous years' questions with solutions
Authentic CBT Mock Tests
Simulate official exam environment with live timer and percentile scoring