arkain101 Posted January 11, 2007 Report Posted January 11, 2007 Question on the momentum of photons: How much momentum does a photon carry for a given intensity? So lets say we use a specific photon value for a specific frequency, and measure the momentum for (t) 1 second. Can we calculate the value of momentum of a photon for specific frequencies? I question this in order to understand how much force one would be met with as they travelled faster and faster and experienced a doppler shift in the light that comes towards them. As I understand, if a source of light traveled directly towards an observer the frequency of the light would increase perportional to the velocity. as calculated: So, would mass traveling faster and faster infact be affected by an ever increasing frequency of photons that have an increasing momentum that forces against that masses acceleration? (assuming I am right in my thinking)One could test special relativity purely with calculations to decifer whether a paradox forms or not. While checking the relationships of the doppler shift, time dilation, and the velocity considerations. I think.. Quote
Farsight Posted January 11, 2007 Report Posted January 11, 2007 Arkain, this is from Mass Explained: When we turn our attention from a cannonball to a photon, we have to express the energy and the momentum in a different way. There is no “mass”, so the energy is hf, and the momentum is hf/c. The h here is Planck’s constant of 6.63 x 10-34 Joule-seconds, and is an “action” which is a momentum multiplied by a distance. The f is the frequency per second, and our old friend c is distance over time, which converts a stopping-distance measure into a stopping-time measure. It’s just λ/c or wavelength over frequency, so you can also express the momentum as h/λ... Yes, the relativistic mass would experience more momentum when running into photons, because they look like they have a higher frequency. It's a bit like driving fast over bumps. I don't think there's any paradoxes to it. Quote
Qfwfq Posted January 11, 2007 Report Posted January 11, 2007 Can we calculate the value of momentum of a photon for specific frequencies?How about: [math]p=\frac{h\nu}{c}=h\lambda[/math] Quote
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