Uncertainty Principle Using ΔEΔt ≥ ħ/2: a 440-Nm Spectral Line

question 16

Multiple Choice

Uncertainty principle using ΔEΔt ≥ ħ/2: A 440-nm spectral line is produced by a transition from an excited state to the ground state. The natural line width of the spectral line is 0.020 pm. The average time the atom spends in the excited state is closest to which of the following? (ħ = 1.055 × 10^-34 J ∙ s = 6.59 × 10^-16 eV ∙ s)

• A) 2.5 × 10^-6 s
• B) 2.5 × 10^-7 s
• C) 2.5 × 10^-8 s
• D) 2.5 × 10^-9 s
• E) 2.5 × 10^-10 s