The Kα X-ray line of tungsten occurs at wavelength λ = 0.21 Å. If the difference between K- and L-shell energy levels is approximately 10x keV, find x.
Physics · Mixed Chapter
JEE Mains

Question

The Kα X-ray line of tungsten occurs at wavelength λ = 0.21 Å. If the difference between K- and L-shell energy levels is approximately 10x keV, find x.

G1 Physics · Accepted Answer

Step 1 — Kα radiation is emitted when an electron moves from the L shell to the K shell. Step 2 — The photon energy equals the K–L energy difference: ΔE = hc/λ. Step 3 — Convert wavelength λ = 0.21 Å = 0.021 nm. Using hc = 1.240 keV·nm, ΔE = 1.240/0.021 = 59.05 keV. Step 4 — As ΔE ≈ 10x keV, 10x ≈ 59.05 ≈ 60, giving x = 6 (nearest integer). Answer: 6.