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I've been doing some physics homework and have gotten all but two of the questions. They are on electron transitions.

#1) In a hypothetical hyrogen like atom the energy of the second energy level is -13.6eV. Calculate the momentum of the electron in the third energy level of this atom.

En = (1/3^2)(13.6) = 1.51 ev

1.51 eV = 2.42 x 10^-19 J

Ek = (1/2)mv^2

square root of (2.42x10^-19J/(0.5 x 9.11 x 10^-31) )

v = 7.3 x 10^5 m/s

p = mv

p = (9.11x10^-31kg)(7.3x10^5m/s) = 6.7 x 10^-25 kg*m/s

The answer should be 1.34 x 10^-24 kg*m/s

I have no idea what I've done wrong

#2) A spectra line in the hydrogen bright line spectra (NOTE: visible region) passes perpendicularily through a diffraction grating (d= 5.00x10^-6m). This spectra line produces a first order maximum at an angle of 4.97 degrees. What is the transition of the elctron that produces this spectra line?

wavelength = (5.00 x 10^-6m)(sin4.97)/1 = 4.33 x 10^-7m

Using Rydberg's equation I subsituted and manipulated and got:

(1/4) - ((1/4.33x10^-7)/1.1x 10^7) then I took the square root of that and got 0.2 which definitely isn't right.

The answer should be 5 to 2. Once again I don't know where I've gone wrong.

Any help is greatly appreciated, thanks in advance!

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# Homework Help: Electron Transitions

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