Post by: tha boss on September 11, 2011, 09:29:04 pm
The wavelength of the scattered photon is closest to:
a) 3.5nm
b) 0.3nm
c) 0.5nm
d) 3.2nm
Post by: Shark 774 on September 13, 2011, 06:39:45 pm
Work function in joules = 5.12 x 10^-19
Kinetic energy of electron in joules = 4.32 x 10^-18
Initial energy of photon = final energy of photon + kinetic energy of electron + energy needed to remove electron (i.e. work function)
Therefore the energy of the scattered photon = the intial photon energy - the kinetic energy of the electron - the energy needed to remove the electron
i.e. E (scattered photon) = 6.63 x 10^-16 - 5.12 x 10^-19 - 4.32 x 10^-18 = 6.58 x 10^-16J
Wavelength of scattered photon = hc/E = 3.022 x 10^-10 = 0.3022 x 10^-9 which is closest to answer B, although of course answer B is rounded, because if it were exactly 0.3 then there would be no change in wavelength and that isn't possible here. Hope this helps.
Post by: thatricksta on September 19, 2011, 08:00:39 am
Initial energy of photon = hc/wavelength = 6.63 x 10^-16J
Work function in joules = 5.12 x 10^-19
Kinetic energy of electron in joules = 4.32 x 10^-18
Initial energy of photon = final energy of photon + kinetic energy of electron + energy needed to remove electron (i.e. work function)
Therefore the energy of the scattered photon = the intial photon energy - the kinetic energy of the electron - the energy needed to remove the electron
i.e. E (scattered photon) = 6.63 x 10^-16 - 5.12 x 10^-19 - 4.32 x 10^-18 = 6.58 x 10^-16J
Wavelength of scattered photon = hc/E = 3.022 x 10^-10 = 0.3022 x 10^-9 which is closest to answer B, although of course answer B is rounded, because if it were exactly 0.3 then there would be no change in wavelength and that isn't possible here. Hope this helps.
This is great, but I must ask - Why do you bother converting to Joules? I think you would have saved time working in eV since plancks constant in eV is 4.14*10-14
Post by: Shark 774 on September 19, 2011, 06:57:13 pm
Initial energy of photon = hc/wavelength = 6.63 x 10^-16J
Work function in joules = 5.12 x 10^-19
Kinetic energy of electron in joules = 4.32 x 10^-18
Initial energy of photon = final energy of photon + kinetic energy of electron + energy needed to remove electron (i.e. work function)
Therefore the energy of the scattered photon = the intial photon energy - the kinetic energy of the electron - the energy needed to remove the electron
i.e. E (scattered photon) = 6.63 x 10^-16 - 5.12 x 10^-19 - 4.32 x 10^-18 = 6.58 x 10^-16J
Wavelength of scattered photon = hc/E = 3.022 x 10^-10 = 0.3022 x 10^-9 which is closest to answer B, although of course answer B is rounded, because if it were exactly 0.3 then there would be no change in wavelength and that isn't possible here. Hope this helps.
This is great, but I must ask - Why do you bother converting to Joules? I think you would have saved time working in eV since plancks constant in eV is 4.14*10-14
Good point! I didn't know the value for planck's constant in terms of eV, but that's a thing I should learn!
Post by: Lasercookie on September 19, 2011, 07:31:45 pm
Good point! I didn't know the value for planck's constant in terms of eV, but that's a thing I should learn!Don't worry, it is on the formula sheet.
thatricksta made a small typo, it's