## Help with Chem Problem!

Cecilia Tsai 3C
Posts: 16
Joined: Fri Sep 25, 2015 3:00 am

### Help with Chem Problem!

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

Chem_Mod
Posts: 18400
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 435 times

### Re: photoelectric effect work function in eV

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?

Cecilia Tsai 3C
Posts: 16
Joined: Fri Sep 25, 2015 3:00 am

### Re: Help with Chem Problem!

she is also in 14a, but with Scerri and we were studying together

Jason118
Posts: 16
Joined: Fri Oct 09, 2015 3:00 am

### Re: Help with Chem Problem!

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.

Chem_Mod
Posts: 18400
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 435 times

Nice work Jason.