ExamBro
ExamBro
CUET · PHYSICS · PYQ PAPER 2025

The smallest wavelength in the spectral lines of the Paschen series of hydrogen atom is: (R is the Rydberg's constant in Å-1)

  1. A 9/R Å
  2. B R/9 Å
  3. C 9R/21 Å
  4. D 21/R Å
Verified Solution

Answer & Solution

Correct Answer

(A) 9/R Å

Step-by-step Solution

Detailed explanation

\( \frac{1}{\lambda} = R \left( \frac{1}{n_f^2} - \frac{1}{n_i^2} \right) \) \( n_f = 3 \), \( n_i = \infty \) for smallest wavelength \( \frac{1}{\lambda} = R \left( \frac{1}{3^2} - \frac{1}{\infty^2} \right) \)…