Light is incident on the surface of metallic sodium, whose work function is 2.3 eV. The maximum speed of the photoelectrons emitted by the surface is 1.26e6 m/s. What is the wavelength of the light?(adsbygoogle = window.adsbygoogle || []).push({});

I first converted Work Function to Joules:

2.3eV x (1.6e-19 J / 1eV) = 3.68e-19 J

The equation I know is:

hf = KEmax + Work Function

hf can also be written as:

hc/lamda

I thought I would substitute c w/ the 1.26e6 m/s and use KEmax as zero. My answer was 2.27e-9m and that is not correct.

I used the following:

f = Work Function / h = 5.55e14 Hz

Then I used:

lamda = v/f = 2.27e-9 m

If I can't substitute v for c, then what am I looking for with v??? I have looked at this problem for 3 days w/ no new ideas. Anyone else have any?

Thank you!!

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# Homework Help: Photons and the Photoelectric Effect

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