# Finding the frequency of a subatomic particle in motion?

If a subatomic particle is moving with an energy equal to 240. mev, what is the frequency associated with this particle ?

E=hv where E = energy of the particle, h = planck's constant and v = frequency

I thought I would solve this by first converting MeV into joules, and then using the equation E=hv to solve for the frequency. However, it seems that was incorrect :(. Maybe my math was incorrect, but I think I'm missing something. I think because the particle is in motion, velocity may be a factor? I'm not exactly sure. Thanks in advance for your help.

Hootenanny
Staff Emeritus
Gold Member
If a subatomic particle is moving with an energy equal to 240. mev, what is the frequency associated with this particle ?

E=hv where E = energy of the particle, h = planck's constant and v = frequency

I thought I would solve this by first converting MeV into joules, and then using the equation E=hv to solve for the frequency. However, it seems that was incorrect :(. Maybe my math was incorrect, but I think I'm missing something. I think because the particle is in motion, velocity may be a factor? I'm not exactly sure. Thanks in advance for your help.
Welcome to Physics Forums.

Your method is indeed correct. If you post your attempted solution, perhaps we could point out where you've gone wrong with the arithmetic.

With regards to your final comment, velocity is indeed a factor but this information is contained within the energy term of Planck's relationship (i.e. the E in your equation). Put simply, the greater velocity the greater the energy of the particle.

Ah okay thanks for clarifying.

As for my solution -

1 MeV = 1.6e-13 J

-- 240 MeV x 1.6e-13 = 3.84e-11 J

-- 3.84e-11 J / 6.626e-34 m2 kg / s = 5.79e22 Hz

Hootenanny
Staff Emeritus
Gold Member
Ah okay thanks for clarifying.

As for my solution -

1 MeV = 1.6e-13 J

-- 240 MeV x 1.6e-13 = 3.84e-11 J

-- 3.84e-11 J / 6.626e-34 m2 kg / s = 5.79e22 Hz
If you're entering your solution online, you need to be careful with rounding. Do not round any intermediate values and ensure that your final answer is given in the required number of sig. figs.