# What are the Units for the momentum of a Photon?

**1. The problem statement, all variables and given/known data**

A photon, a packet of electromagnetic radiation, carries both energy and momentum. Consider a photon with a wavelength of 428 nm in vacuum.

A) What is the frequency of the photon? 7.01×1014 Hz CORRECT

B) What is the energy of the photon? 4.64×10-19 J

C) What is the momentum of the photon?

**2. Relevant equations**

P=m*V

Plancks Constant: (6.6262E-34 J/s)

**3. The attempt at a solution**

A) (3E8 m/s) / (4.28E-7 m) = 7.009E14 Hz CORRECT

B) (7.009E14 Hz) * (6.6262E-34 J/s) = 4.644E-19 J CORRECT

This is where I need Help

C) What is the momentum of the photon?

[(7.009E14 Hz)*(6.6262E-34 J/s)] / (3E8 m/s) = 1.546E-27

I think I have the number but I can’t submit it to check it, until I have the right unit of measurement. I tried (Hz*m/s), (m/s), (nm*m/s).

If I don’t have the number right would you let me know as well.

http://ift.tt/1j2Kiuq

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