Calculate Longest & Shortest Wavelength?

Electrons accelerated by a potential difference of 13.14 V pass through a gas of hydrogen atoms at room temperature.

A) Calculate the wavelength of light emitted with the longest possible wavelength.

B) Calculate the wavelength of light emitted with the shortest possible wavelength.

I’ve solved part B, but cannot solve part A. Any suggestions?

Part B [CORRECT]
V=13.14V so KE=13.14 eV

En=-13.6/(n^2)
E1= -13.6 eV

E= -13.6 eV + 13.14 eV
E= -0.45 eV

E2= -3.4 eV
E3= -1.5 eV
E4= -0.85 eV
E5= -0.544 eV
E6= -0.378 eV

E=E5-E1
E=(-0.544)-(-13.6)
E= 13.056eV * 1.6e-19 J
E= 2.089e-18 J

E=hc/λ
λ=hc/E
λ=(6.626e-34)*(3e8)/(2.089e-18)
λ= 9.52e-8 m

Attempt at Part A) [INCORRECT]

Longest wavelength is in Paschen series (n=3)
E=E4-E3
E=(-0.85)-(-1.5)
E= 0.65eV * 1.6e-19 J
E= 1.04e-19 J

E=hc/λ
λ=hc/E
λ=(6.626e-34)*(3e8)/(1.04e-19)
λ= 1.91e-6 m

http://ift.tt/1plhVLs

Leave a comment

Your email address will not be published.


*


Show Buttons
Hide Buttons