## De Broglie Equation Derivation and Use

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

Yazmin Bocanegra 3L
Posts: 51
Joined: Thu Jul 25, 2019 12:17 am

### De Broglie Equation Derivation and Use

How do you derive the De Broglie equation and when do you use it?

AronCainBayot2K
Posts: 101
Joined: Fri Aug 30, 2019 12:17 am

### Re: De Broglie Equation Derivation and Use

De Broglie Equation is used to find the wavelength of a particle with momentum, usually dealing with an electron. The equation is wavelength (lambda)=h/p where p can be rewritten as mass * velocity, while h represents Planck's constant.

Charisse Vu 1H
Posts: 101
Joined: Thu Jul 25, 2019 12:17 am

### Re: De Broglie Equation Derivation and Use

We don't necessarily need to know how to derive De Broglie's Equation. Just know that De Broglie's Equation is used when calculating the wavelength or frequency of anything with mass, such as electrons.

Rosa Munoz 2E
Posts: 105
Joined: Wed Sep 18, 2019 12:21 am

### Re: De Broglie Equation Derivation and Use

You don't have to know how to derive it.

RasikaObla_4I
Posts: 100
Joined: Thu Jul 25, 2019 12:15 am

### Re: De Broglie Equation Derivation and Use

It is derived from the equations E=momentum * speed of light and E= hc/wavelength. Combining both of those, you get wavelength= h/momentum. You use the de Broglie equation for any particle with momentum and wavelength properties.

TarynD_1I
Posts: 100
Joined: Sat Aug 24, 2019 12:17 am

### Re: De Broglie Equation Derivation and Use

You use de Broglie's equation to find the wavelength of a particle that has resting mass (not light/photons).

CalvinTNguyen2D
Posts: 102
Joined: Thu Jul 25, 2019 12:16 am

### Re: De Broglie Equation Derivation and Use

De Broglie's equation can be used for any particle or object with a mass and velocity (momentum)!

Mulin_Li_2J
Posts: 105
Joined: Sat Aug 17, 2019 12:16 am

### Re: De Broglie Equation Derivation and Use

The derivation of De Broglie Equation takes three other equations. The first one is E = mc²; the second one is E = hv; the third one is c = vλ.

First, we take c = vλ, transform it to be v = c/λ, and replace it with v in E = hv. Then we get E = h*c/λ .

Second, we transform E = mc² to E = m*c*c. Since p(momentum) = m*c, we can write E = m*c*c as E = p*c.

Thrid, we let the two transformed equation equal to each other. We get p*c = h*c/λ. Cancel c from both sides, we get p=h/λ.

Finally, switch p and λ in the equation p=h/λ based on the rule of a equation, we get λ = h/p, which is the De Broglie Equation.

I know why you are asking this question because Dr. Lavelle writes it on his course outlines. I don't know whether we are gonna have it on a test, but it's always good to know more equations than less.

Hope this can help!