De Broglie Derivation

[Megan Bundy 2K]

Do we need to know the steps of deriving the De Broglie equation?

[sgarza]

I don't think so, I think Dr. Lavelle only showed us the derivation in class in order for us to understand the connection between the equations that we have been learning. And also that if we forget the de broglie equation, we can derive it ourselves using the other energy equations.

[Madysen Ratsek 3L]

Hi Megan! Good question. I do not think we need to know how to derive the de Broglie equation, but it is important to note that since lambda=h/p, lambda also equals h/mv, since p=mv (mass*velocity). This is especially useful for when we are just given the velocity of a particle (ie. an electron) and can infer the mass, and use it to solve for the wavelength of the particle! I hope this helps.

[Ivan Huang Dis 3B]

I think we just need to know when and how to use it not how it came to be

[Quynhanh Nguyen 1C]

Hey there!

I would assume that for all upcoming exams, we will need to know the De Broglie Derivation because it is on our learning objectives outline. Luckily, it's quite simple!

Knowing: c = h(lambda) and E = hv, we can conclude that E = hc/ (lambda)

We also know that E = pc

Therefore, pc = hc/ (lambda)

The speeds of light cancel out. If you rearrange the equation for lambda, you get lambda = h/p which is De Broglie's equation. Hope this helps!

[Patricia Sourinphoumy Dis1C]

Hi! I think that the outlining of how the De Broglie equation was derived was just something supplemental. It was also pretty motivating to see how things connected! I will say that it definitely reminds you of what other variables (like those mentioned in replies above mine) might be involved when solving a De Broglie problem.

[Litsa Dimit 1D]

It is helpful to know where it came from and how to derive it, but it is not necessary to memorize!

[Gabriel Wolf 3I]

I don't believe so. If you do, it's just setting E=hv and E=pc to each other and solving for lamba (c=lambav). What you should note, however, is that this equation, despite its usage of c=lambav, should not be used to solve for light, as light has no resting mass.

[505686385]

Hello. No I do not think we need to know the derivation of De Brogiles equation. We know that wavelength = h/p, which is Plank's Constant divided by momentum. We can find momentum by multiplying the mass of the object by its velocity. So wavelength = h/mv. Hope this helps!