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# Photoelectric effect watch

1. Sorry about the awful quality. The numbers marked on the frequency axis are 5 x 1014 and 10 x 1014.

From reading the graph I got that the threshold frequency is 7 x 1014 but I'm lost with working out which metal it is. Any hints and help greatly appreciated.
2. (Original post by C274)

Sorry about the awful quality. The numbers marked on the frequency axis are 5 x 1014 and 10 x 1014.

From reading the graph I got that the threshold frequency is 7 x 1014 but I'm lost with working out which metal it is. Any hints and help greatly appreciated.
Not sure if this is right because I don't remember a lot of this even though I've done this a few weeks ago.

Anyways the threshold frequency is the minimum frequency required to release electrons from the metal surface so if you extrapolate it down towards the x axis you should get 6.5x10^14(that was like so hard to read lol) then as its the minimum frequency, kinetic energy is 0, therefore you can use: hf=work function (hf=work function+ke where ke=0)
h=6.63x10^-34 (can't believe i still remember that , then multiply that by your threshold frequency , that is , 6.5x10^14 and you should get approximately 4.9x10^-19 and that corresponds to calcium.

Hope that helps.
3. Ahh, thank you!

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