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Help with Chem Problem!

Posted: Tue Oct 20, 2015 6:23 pm
by Cecilia Tsai 3C
A friend asked me to help her with a chemistry problem, but I'm not sure how to do it.

Which of the following metals requires UV light to exhibit the photoelectric effect?
a) Cs, Work function= 1.95 eV
b) Ag, Work function= 4.74 eV
c) K, Work function= 2.29 eV
d) Y, Work function= 2.90 eV

Re: photoelectric effect work function in eV

Posted: Tue Oct 20, 2015 6:50 pm
by Chem_Mod
Convert the eV to J.
1 eV = 1.6022 x 10-19 J
Then use E = hv to convert to v.

What class is she in?

Re: Help with Chem Problem!

Posted: Tue Oct 20, 2015 6:56 pm
by Cecilia Tsai 3C
she is also in 14a, but with Scerri and we were studying together

Re: Help with Chem Problem!

Posted: Tue Oct 20, 2015 7:57 pm
by Jason118
v = E/h
for Cs: v = 4.71 x 10^14 Hz
for Ag: v = 1.15 x 10^15 Hz
for K: v = 5.54 x 10^14 Hz
for Y: v = 4.38 x 10^14 Hz

Range of ultraviolet light frequency is 7.5 x 10^14 Hz - 3 x 10^17 Hz, so the only metal that is in the range is Ag.

Re: Help with Chem Problem!

Posted: Tue Oct 20, 2015 11:36 pm
by Chem_Mod
Nice work Jason.