## De Broglie vs. speed of light/Einstein equation

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

Amy Dinh 1A
Posts: 62
Joined: Fri Sep 28, 2018 12:23 am

### De Broglie vs. speed of light/Einstein equation

When would you use De Broglie's equation (E=h/p) compared to using the Einstein equation (E=hc/lambda)?

705192887
Posts: 77
Joined: Fri Sep 28, 2018 12:18 am

### Re: De Broglie vs. speed of light/Einstein equation

De Broglie's wavelength equation is used for particles and objects, such as electrons or a baseball, while the speed of light/Einstein equation is used only when calculating the wavelength or frequency of light. C=λv can't be used with particles because it describes a relationship with light. This is an important—yet often unrealized—distinction. I messed up on the last test by using E=hv and C=λv to calculate the wavelength of an electron, when De Broglie should've been used. Hope this helps!

Kayla Vo 1B
Posts: 60
Joined: Fri Sep 28, 2018 12:26 am

### Re: De Broglie vs. speed of light/Einstein equation

λ=h/p (Broglie wavelength) is used when you need to find the wavelength of a particle (e.g. an electron) with a certain speed. On the other hand, E=hc/λ is used to find the wavelength of a photon of a certain energy

Eunice Lee 1A
Posts: 60
Joined: Wed Oct 03, 2018 12:16 am

### Re: De Broglie vs. speed of light/Einstein equation

The Einstein equation can only be used for photons, while the De Broglie equation can be used for anything.