Department of Pre-University Education, Karnataka course PUC Karnataka Science Class 12
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# The Wavelengths of Kα and Lα X-rays of a Material Are 21.3 Pm and 141 Pm Respectively. Find the Wavelength of Kβ X-ray of the Material. - Physics

ConceptElectromagnetic Spectrum

#### Question

The wavelengths of Kα and Lα X-rays of a material are 21.3 pm and 141 pm respectively. Find the wavelength of Kβ X-ray of the material.

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

#### Solution

Given:-
Wavelength of Kα X-ray, lambda_1 = 21.3  "pm"

Wavelength of Lα X-ray, lambda_2 = 141  "pm"

Energy of Kα X-ray (E_1) is given by

E_1 = 1242/(21.3 xx 10^-3)

= 58.309 xx 10^3  "eV"

Energy of Lα X-ray (E_2) is given by

E_2 = 1242/(141 xx 10^-5)

= 8.8085 xx 10^3  "eV"

Energy of Kβ X-ray (E_3) will be

E_3 = E_1 + E_2

E_3 = (58.309 + 8.809) xx 10^3  "eV"

E_3 = 67.118 xx 10^3  "eV"

Wavelength of Kβ X-ray (lambda) is given by

lambda = (hc)/(E_3) = 1242/(67.118 xx 10^3)

= 18.5 xx 10^-3  "nm" = 18.5  "pm"

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Solution The Wavelengths of Kα and Lα X-rays of a Material Are 21.3 Pm and 141 Pm Respectively. Find the Wavelength of Kβ X-ray of the Material. Concept: Electromagnetic Spectrum.
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