Let λ₁ be the Kα wavelength of copper (Z = 29) and λ₂ the Kα wavelength of molybdenum (Z = 42). Find λ₁/λ₂.
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Question

Let λ₁ be the Kα wavelength of copper (Z = 29) and λ₂ the Kα wavelength of molybdenum (Z = 42). Find λ₁/λ₂.

G1 Physics · Accepted Answer

Step 1: Moseley's law for Kα gives 1/λ ∝ (Z−1)². Step 2: Therefore λ₁/λ₂ = [(42−1)/(29−1)]² = (41/28)². Final: use this value and select the keyed option.