Q. Energy levels A, B and C of a certain atom correspond to increasing values of energy i.e., E_A < E_B < E_C. If λ₁, λ₂ and λ₃ are wavelengths of radiations corresponding to transitions C to B, B to A and C to A respectively, which of the following relations is correct ?
A) λ₃ = λ₁ + λ₂
B) λ₃ = λ₁λ₂/(λ₁ + λ₂)
C) λ₁ + λ₂ + λ₃ = 0
D) λ₃² = λ₁² + λ₂²
Explanation
[Solution from source] Photon energies add: hc/λ₃ = hc/λ₁ + hc/λ₂, so 1/λ₃ = 1/λ₁ + 1/λ₂ and λ₃ = λ₁λ₂/(λ₁ + λ₂). Adding the wavelengths directly is wrong because energy, not wavelength, is additive. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.