Hi all,(adsbygoogle = window.adsbygoogle || []).push({});

I'm trying to understand work functions and am working through a paper but keep coming up with the wrong answer. Can anyone point out where I'm going wrong please...

Wavelength of light incident on surface = 560 nm

Max speed of ejected electrons = 1.67 x 10^{5}ms^{-1}

1 eV = 1.602 x 10^{-19}J

I'm using 0.5mv^{2}=hf-ø rearranged as ø=hf-0.5mv^{2}

Putting in the figures above:

=(6.63 x 10^{-34}) x (1 / (5.6 x 10^{-19})) - 0.5 (1.67 x 10^{5})^{2}x 9.109 x 10^{-31}

= 1.18 x 10^{-27}- 12.70 x 10^{-21}= -1.27 x 10^{-20}J

I'm sure I'm not meant to come up with a negative answer.

Many thanks for any assistance you can give.

Bob

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Work Function Question

**Physics Forums | Science Articles, Homework Help, Discussion**