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A certain element emits Kalpha X-ray of ...

A certain element emits `K_alpha` X-ray of energy 3*69 keV. Use the data from the previous problem to identify the element.

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Given E=3.69KeV=3690eV `
` lambda=(hc)/E=1242/3690=0.33658nm `
` sqrt(c/lambda)=a(Z-b) `
` a=5xx10^7sqrtHz `
` b=1.37 `
` (from previous problem) `
` sqrt((3xx10^8)/(0.34xx10^-9))=5xx10^7(Z-1.37) `
` rArr sqrt(8.82xx10^17)=5xx10^7(Z-1.37) `
` rArr 9.39xx10^8=5xx10^7(Z-1.37) `
` rArr 93.9/5=Z-1.37 `
` Z=93.9/5+1.37 `
` =20.15=20 `
So, The element is calcium
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