Why does a massless photon have momentum?
Why does a massless photon have momentum?
In short, even though photons have no mass, they still have momentum proportional to their energy, given by the formula p=E/c. Because photons have no mass, all of the momentum of a photon actually comes from its energy and frequency as described by the Planck-Einstein relation E=hf.
What is the momentum of a photon?
The momentum of a photon, p, measured in kilogram meters per second, is equal to Planck’s constant, h, divided by the de Broglie wavelength of the light, lambda, measured in meters (p = h / lambda).
How can photon have no mass?
Why do photons have no mass? In short, the special theory of relativity predicts that photons do not have mass simply because they travel at the speed of light. This is also backed up by the theory of quantum electrodynamics, which predicts that photons cannot have mass as a result of U(1) -gauge symmetry.
What is a massless photon?
In particle physics, a massless particle is an elementary particle whose invariant mass is zero. The two known massless particles are both gauge bosons: the photon (carrier of electromagnetism) and the gluon (carrier of the strong force). Neutrinos were originally thought to be massless.
What is the value of mass of photon?
According to electromagnetic theory, the rest mass of photon in free space is zero and also photon has non-zero rest mass, as well as wavelength-dependent. The very recent experiment revealed its non-zero value as 10 – 54 kg ( 5.610 × 10 – 25 MeV c – 2 ) .
How is light affected by gravity if photons are massless?
Originally Answered: Since photons have no mass, how can gravity bend light? Gravity doesn’t bend light, rather it distorts space-time. The effect we see is due to light following a ‘straight’ path through curved space-time.
Can a massless object have momentum?
This is given as a solution to the problem of only massive objects being affected by gravity. However, momentum is the product of mass and velocity, so, by this definition, massless photons cannot have momentum.
How can massless particles have momentum?
A massless particle can have energy E and momentum p because mass is related to these by the equation m2 = E2/c4 – p2/c2, which is zero for a photon because E = pc for massless radiation.
How can a massless particles have momentum?
Why are massless photons affected by gravity?
Matter and energy curve spacetime, and curved spacetime tell both matter and energy how to move. That’s why masses can exert a gravitational influence on photons: they curve space. The photon has no choice of what it needs to do.
Why does photon have mass?
Since photons (particles of light) have no mass, they must obey E = pc and therefore get all of their energy from their momentum. But an object with zero energy and zero mass is nothing at all. Therefore, if an object with no mass is to physically exist, it can never be at rest. Such is the case with light.
Do photons have momentum if they have no mass?
In short, even though photons have no mass, they still have momentum proportional to their energy, given by the formula p=E/c. Because photons have no mass, all of the momentum of a photon actually comes from its energy and frequency as described by the Planck-Einstein relation E=hf.
Is a photon a massless particle?
When people claim that a photon is massless, they mean that a photon has zero rest mass. with $\\lambda$ being the wavelength of light. So it can have an energy, while still being massless. No, a photon does not need to have mass to be able to interact with matter.
How can a photon gain mass?
Through processes that involve the electromagnetic interaction in general and accelerating, vibrating or jumping electrons in particular. When people claim that a photon is massless, they mean that a photon has zero rest mass. In special relativity, the formula for the energy of a particle with mass m possessing a momentum p is
What is the rest energy of a photon?
Photons are indeed massless and thus have zero rest energy. This is not an issue because according to special relativity, they do not come with a rest frame. Please note that assuming we denote rest mass by m, the well-known E = m c 2 is not the whole story – the general formula reads E 2 = m 2 c 4 + p 2 c 2
