## Where does Planck's Constant Come From

$E=hv$

Ben Rolnik 1D
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Joined: Fri Jun 23, 2017 11:39 am

### Where does Planck's Constant Come From

Can someone explain where Planck's constant comes from? I understand how to use it... but what exactly does it mean?

I read in the book that the smallest quantity we study in chemistry is 10^-34 (where "space breaks down")... and since ( h = 6.698 x 10^-34 ) I'm very curious what this actually means? Is this the smallest quantity in the universe?

Thanks!
Ben 1D

Chem_Mod
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### Re: Where does Planck's Constant Come From

It can be obtained from the slope of a plot: E versus frequency
That is, measure photon energy for a given frequency. Then plot energy (y-axis) vs frequency (x-axis) and the slope is Planck's constant.

Yes it is the smallest known constant.

JD Malana
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Joined: Wed Nov 16, 2016 3:02 am

### Re: Where does Planck's Constant Come From

Kinda cool how scientists have discovered such an "unspeakably small" constant as my TA would describe it...even more amazing that such a minute constant was observed rather than arbitrarily chosen, meaning that there are relationships between things in the universe that actually rest upon such small numbers..what would happen to the universe if Planck's constant changed by even the tiniest amount by just like 3x10-34 or some other number that small?

Chem_Mod
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### Re: Where does Planck's Constant Come From

A small change in Planck's constant, the gravitational constant, etc., would all be significant. Analyzing this quantitatively would be an interesting project.

It also makes for good science fiction writing. A good science education is a great start for good sci-fi writers.

Ben Rolnik 1D
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Joined: Fri Jun 23, 2017 11:39 am

### Re: Where does Planck's Constant Come From

Thank you for the response!!

And I'm digging the sci-fi connection :)

Wayland Leung
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### Re: Where does Planck's Constant Come From

This is a good question as I was wondering the same thing. Based off the reading from the textbook, I can make an educated guess that he conducted an experiment about the photoelectric effect to come up with the constant value. He proposed in his experiment that energy travels in packets.