Physics -- deriving Planck's constant

[YungSung]

hello,

im trying to do this homework, where i have to derive Plancks constant using an experiment where we used some LED lights of different wavelengths to work out voltage at different wavelengths. From that i worked out the frequency and ekmax of the electrons given out. however i have no idea how to derive Plancks constant from this and my teacher was rushing everything so no one understood anything, i don't know the reason behind why we did the experiment in that way.

why did LED lights light up and isn't the photoelectric effect the release of electrons? so why were we seeing whther the LED was lighting up or not at different resistaances?

please help thanks

 

[MisterX]

Is there some way you might be able to provide us with a scan of the relevant sections of your lab manual?

 

[YungSung]

this is as level, there is no lab manual

 

[YungSung]

we need to plot a graph and the gradient of that graph will be Plancks constant

 

[Jilang]

Energy can be measured in electron volts (eV) where e is the electron charge, if that helps.

 

[Heisenberg_white]

I know I am really late to answer this question, but it might help others. I have attached an image, so refer to that. Do ping if you can't understand or want more information :)

 

[Steve4Physics]

... have to derive Plancks constant using an experiment where we used some LED lights of different wavelengths to work out voltage at different wavelengths. From that i worked out the frequency and ekmax of the electrons given out.
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why did LED lights light up and isn't the photoelectric effect the release of electrons? so why were we seeing whther the LED was lighting up or not at different resistaances?

The photoelectric effect is a process in which incident photons knock out electrons from a conductor's surface or from atoms. This is not the process that occurs in LEDs.

In a (very loose) sense, light production in LEDs is the reverse of the photoelectric effect.

An LED lights up when a minimum voltage is applied (which could be the result of, for example, changing resistance in your experiment).

Have you tried Googling (or whatever you use) "Planck's constant from LEDs"? There is loads of information, including YouTube videos.

And "plancks" should of course be "Planck's"!