What is the momentum of a photon given by?

The momentum of a photon is indeed given by the equation that relates momentum to its wavelength. The correct expression is derived from considering the energy of a photon, which is given by E = hf, where h is Planck's constant and f is the frequency of the photon. Since the speed of light (c) is related to frequency and wavelength by the equation c = f * wavelength, we can rearrange it to find frequency and substitute back into the energy equation.

The equation for momentum in terms of wavelength can be expressed as follows:

1. Start with the definition of energy: E = hf.

2. Substitute for frequency: f = c / wavelength.

3. This gives E = h(c / wavelength), which simplifies to E = (hc) / wavelength.

4. The momentum p of a photon can then be expressed as p = E/c, leading us to p = (hc/wavelength) / c = h/wavelength.

This is coherent with the original statement that the momentum of a photon can also be expressed as p = h/wavelength, demonstrating that the momentum is directly related to the photon’s properties.

The other choices provided relate to different contexts in physics. Momentum denoted as p = mv applies specifically to objects