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### Topic: Calculate the longest possible wavelength, in nanometer...  (Read 6723 times)

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#### zerox0o

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##### Calculate the longest possible wavelength, in nanometer...
« on: September 19, 2009, 03:43:47 PM »
If it takes   3.92 × 10−19 J   of energy to eject an electron from the surface of a certain metal, calculate the longest possible wavelength, in nanometers, of light that can ionize the metal.

How do I do this? I am really clueless...

thank you!!!

#### DrCMS

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##### Re: Calculate the longest possible wavelength, in nanometer...
« Reply #1 on: September 19, 2009, 03:53:38 PM »
How do you calculate the energy of light of a particular wavelength?  Hint Planck's constant is needed.

#### zerox0o

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##### Re: Calculate the longest possible wavelength, in nanometer...
« Reply #2 on: September 19, 2009, 04:00:46 PM »
How do you calculate the energy of light of a particular wavelength?  Hint Planck's constant is needed.

(energy) = (Planck constant)(frequency) - (work function)

(speed of wave) = (frequency)(wavelength)

E = hc/λ - φ
λ = hc/(E + φ)

k i got it! thanks

« Last Edit: September 19, 2009, 04:17:54 PM by zerox0o »