Wednesday
June 19, 2013

# Homework Help: physics

Posted by jason on Sunday, April 22, 2012 at 5:29pm.

The Kβ characteristic X-ray line for tungsten has a wavelength of 1.94 10-11 m. What is the difference in energy between the two energy levels that give rise to this line? Express this in each of the following units.

(a) joules

(b) electron volts

• physics - Elena, Sunday, April 22, 2012 at 6:05pm

Moseley's law
1/λ = R (Z σ)^2(1/n^2 -1/m^2)
R=1.110^7 m^-1 is the Rydberg constant,
Z = 74,
σ = 1 for K-series,
for K-β: n = 1, m = 3.
ε = hc/ λ,
where
h = 6.6310^-34 Js is the Plancks constant,
c = 310^8 m/s is the speed of light.
So
ε = hc /λ = 6.6310^-34 310^8  1.110^7  (74 1)^2(1 - 1/9) = 1.03610^-14 J =6.4710^4 eV.

• physics - Damon, Sunday, April 22, 2012 at 6:09pm

distance = speed * time
1.94*10^-11 = 3 * 10^8 * T
f = 1/T = 3*10^8/1.94*10^-11

E=h f =6.6*10^-34 * 3 *10^8/(1.94*10^-11)
in Joules

Electron volt - 1.6 * 10^-19 Joules

• physics - Elena, Sunday, April 22, 2012 at 6:17pm

Distance in energy is
ΔE which is equal to the energy of the quantum ε

• Elena - they gave us Lambda - Damon, Sunday, April 22, 2012 at 6:20pm

the wavelength was given.
You had me puzzled there for a while.

• physics - Elena, Sunday, April 22, 2012 at 6:32pm

I've tried to give the method of determination, especially taking into account another Jason's question

• physics - Damon, Sunday, April 22, 2012 at 6:35pm

I see, cool :)

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