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When describing photons specifically rest mass is zero. The "rest mass" is the hypothetical mass a photon would have if it weren't moving at the speed of light, which as just stated, is zero. Nothing with a non-zero rest mass can travel at the speed of light in a vacuum, because it would require a literally infinite amount of energy to accelerate to that speed. (Neutrinos have a very small, but non-zero, rest mass, and therefore travel at most at slightly under the speed of light.)
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What type of mass is light?
Light 'particles' (photons) have no rest mass.
What is the difference between photons and electrons?
Photons have no charge, no rest mass and travel at the speed of light throuh a vacuum. Electrons have a charge of -1, have rest mass and are part of atoms.
What is the Difference between electrons and photons?
Photons have no charge, no rest mass and travel at the speed of light throuh a vacuum. Electrons have a charge of -1, have rest mass and are part of atoms.
Do photon have a greater energy than electron?
No. A photon has no rest mass an electron has mass.
Must a particle have non-zero rest mass in order to have momentum?
Yes. A particle of zero rest mass has ONLY its relativistic mass when in motion. There are actually no photons just sitting around.
How do photons exert force if force is mass times acceleration and photons have no rest mass and travel at constant speed?
The problem in the posed question is the "mass" in the equation you quote is the mass of the object upon which the force (whether it be a photon or not) is acting, NOT the mass of the object exerting the force. You can MEASURE the net force on an object with mass simply by measuring the acceleration of that object and dividing it by the object's mass. Or you can predict an acceleration of an object with mass by calculating what its net force will be, and then dividing that by the object's mass. Unrelated to the above excellent answer, but another comment on the question: You mention, correctly, that photons have no rest-mass. But the photon is never at rest, and at the speed at which it moves from place to place, it has mass.
Do photons physically move or displace opsin molecules of rhodopsin and if so how do they do so since photons have nearly 0 mass do they use their mass or some type of energy transfer?
Photons have energy, therefore they have both mass, and momentum. (Note: They do have a "rest mass" or "invariant mass" of zero, which basically means that they can only move at the speed of light.) Photons of high energy (and high mass, and high momentum) can destroy molecules, or even atoms.
What is the differences between a w boson and a virtual photon?
W-bosons are charged and the photons are uncharged, W-bosons have a non zero rest mass and photons hsve zero rest mass. Also the W-boson is the "exchange particle" in interactions involving the weak nuclear force, but photons are the exchange particle of the electromagentic force.
Does light have weight?
If light is made of photons and photons have mass then you would assume that light has weight in a gravitational field. In fact light running into an object imparts momentum to it. However photons have no rest mass. If they did , objects that were exposed to sunlight and absorbed it would get heavier as time goes on, they don't. So light has no mass and hence no weight.
What is the mass of all photons from the sun striking the Earth in a year?
Mass of photons? Zero, photons have no mass. If you mean energy, that is a different question, ask it.
Do photons of a different energy have the same mass?
Yes... and that mass would be Zero. Photons don't have mass.
A particle of electromagnetic radiation with no mass that carries a quantum of energy?
Bear in mind that anything that has energy also necessarily has some amount of mass, however small, in accordance with the famous equation e = mc2. Photons are said to have no rest mass, but since they are never at rest that is a purely theoretical characteristic. Photons have no mass other than the small amount to which their energy content is equivalent.
