### Deriving the function

Posted:

**Tue Oct 10, 2017 4:30 pm**I am uncertain how to derive the DeBroglie Equation from the E=mc^2 equaiton. Is it necessary to know how to derive this function?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=18&t=22046

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Posted: **Tue Oct 10, 2017 4:30 pm**

I am uncertain how to derive the DeBroglie Equation from the E=mc^2 equaiton. Is it necessary to know how to derive this function?

Posted: **Tue Oct 10, 2017 4:46 pm**

You do not need to know how to derive ay equations. On the test you will be given a formula sheet that will include the de Broglie equation.

Posted: **Wed Oct 11, 2017 10:28 am**

Does de Broglie's equation apply to particles of matter as well as photons of electromagnetic radiation?

Posted: **Fri Oct 13, 2017 4:46 pm**

Yes, De Broglie's equation applies to everything that has momentum (so your particle must have mass and velocity).

I think it was derived by relating quantum mechanics to classical mechanics. So,

E = mc^2 and E = hf

E = mc^2 = hf **set equations equal to one another**

E = mc^2 = h(c/λ) **substitute for frequency **

mc = h/λ **cancel the c's**

λ = h/mc **rearrange**

λ = h/mv **since c is the speed of light, if we had to apply this equation to other things, c would just be the speed of that thing (v)**

I think it was derived by relating quantum mechanics to classical mechanics. So,

E = mc^2 and E = hf

E = mc^2 = hf **set equations equal to one another**

E = mc^2 = h(c/λ) **substitute for frequency **

mc = h/λ **cancel the c's**

λ = h/mc **rearrange**

λ = h/mv **since c is the speed of light, if we had to apply this equation to other things, c would just be the speed of that thing (v)**

Posted: **Fri Oct 13, 2017 6:10 pm**

When is it necessary to use this functions again?

Posted: **Sat Oct 14, 2017 6:54 pm**

Tatiana R Dis 3E wrote:When is it necessary to use this functions again?

The de Broglie equation is used to measure the wavelength of the ejected electron.