Difference between DeBrogile and Light

$\lambda=\frac{h}{p}$

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Connie2I
Posts: 29
Joined: Fri Sep 29, 2017 7:07 am

Difference between DeBrogile and Light

How do we know to differentiate between using the DeBrogile equation and the equation of c = (wavelength) (frequency)?
For example, when we are given the frequency and asked to find wavelength, how do we know whether or not to use one equation rather than the other since both variables
are present in both equations?

Sophie 1I
Posts: 51
Joined: Fri Sep 29, 2017 7:04 am

Re: Difference between DeBrogile and Light

The De broglie equation is wavelength=h/p where p=mv with the v relating to velocity of a particle not the frequency. If you were given the frequency and asked to find the wavelength you would use c=wavelength times frequency.
So basically you use De broglie when comparing wavelength to its mass and speed.

Chem_Mod
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Joined: Thu Aug 04, 2011 1:53 pm
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Re: Difference between DeBrogile and Light

The speed of light equation is for light, which does not have mass. The deBroglie equation is for particles and objects with mass. Though they both include wavelength, they do not refer to the same thing.

If the question gives you frequency and asks you to solve for wavelength, this appears to be a light question.

Hope this helps.

Mohamad 1J
Posts: 15
Joined: Mon Apr 09, 2018 1:39 pm

Re: Difference between DeBrogile and Light

You can decide which equation to use depending on what you are working with. If it is something with mass then you can use the DeBrogile equation, but as particles of light have no mass you cannot use that equation. So for light you would you the c=(wavelength)(frequency). Hope this helps!

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