## if light does not have mass...

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

Funmi Baruwa
Posts: 108
Joined: Wed Sep 30, 2020 9:50 pm

### if light does not have mass...

This question may be asking to understand too much, but I'm a little curious.

If we use De Broglie's equation to find the wavelength/show the wavelike properties of a particle, then how come the equation was derived from equations used for light?

I thought light does not have mass, so how can we use light as a reference for an equation that requires mass??

I hope my question makes sense lol

Megan Sparrow 1A
Posts: 105
Joined: Wed Sep 30, 2020 9:49 pm
Been upvoted: 4 times

### Re: if light does not have mass...

You are correct, light does not have mass. It does, however, have momentum. Since photons (particles of light) have no mass, they must obey E = pc and therefore get all of their energy from their momentum. This is why the DeBroglie equation works in this instance. Hope this helps!

Funmi Baruwa
Posts: 108
Joined: Wed Sep 30, 2020 9:50 pm

### Re: if light does not have mass...

thanks!! that clears it up :)