Moderate

If the lowest energy X-rays have λ = 3.055×10⁻⁸ m, estimate the minimum Z at which a transition from n=2 to n=1 would emit an X-ray.

Correct answer: A. Z=2

A. Z=2
B. Z=3
C. Z=4
D. Z=5

Explanation

First, the energy of the X-ray is calculated as E = hc/λ ≈ 40.6 eV. The energy of the n=2 to n=1 transition is ΔE = 10.2 Z². Setting 10.2 Z² = 40.6 and solving for Z gives Z ≈ 2. The minimum integer atomic number is 2.

Last updated 1 September 2026

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If the lowest energy X-rays have λ = 3.055×10⁻⁸ m, estimate the minimum Z at which a transition from n=2 to n=1 would emit an X-ray.

About Atomic Structure

Practise Atomic Structure

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