## Photons? [ENDORSED]

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

Emily Glaser 1F
Posts: 156
Joined: Thu Jul 27, 2017 3:01 am

### Photons?

Is the DeBroglie Equation only applicable to non-photon objects? Are photons the fastest particle ever?

Chem_Mod
Posts: 18400
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 435 times

### Re: Photons?

Yes and Yes

As discussed in my Wednesday review session the DeBroglie Equation applies to particles with rest/real mass that are moving.

You can also discuss this today (Thursday) in the many support hours I have organized:

Chemistry & Biochemistry, 4222 Young Hall
Victoria Ford 12-1 pm, Ronald Yang 12-1 pm, Karen Leung 1-2pm

STEM Learning Center, Boelter Science & Engineering Library 8251
Franklin Liu 2-4 pm

Five (physical) hours available today (Thursday), in addition to Chemistry Community.

Kellina Tran 2I
Posts: 50
Joined: Sat Jul 22, 2017 3:00 am

### Re: Photons?

Yes, so if you are trying to find the wavelength of an ejected electron, you must use the De Brogile equation an its momentum. You cannot use E = hv and other extensions of it.

Mei Blundell_1J
Posts: 32
Joined: Fri Apr 06, 2018 11:01 am
Been upvoted: 1 time

### Re: Photons?

I'm unclear on why E=h/p can't be used for photons. After all, photons do have momentum p and E=h/p is derived from equations that describe photons, so why doesn't E=h/p also describe photons? Photons don't have mass but they do have momentum, so I don't see why E=h/p can't be used for photons. I'm pretty sure the answer has to do with E=mc^2, but I'm having trouble making the connection. Please help. Thanks

Sam Metzger 1C
Posts: 25
Joined: Wed Apr 04, 2018 3:00 am

### Re: Photons?  [ENDORSED]

Photons do not have a REST mass, which is another criteria for the equation to stand. Although a photon may have p, because they don't have a rest mass they do not apply to the De Broglie equation.