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Photons have zero rest mass, but at the speed at which they move ... always the speed of light ... they have momentum, energy, and mass. Photon energy = (h n) Kinetic energy = (1/2 m c2) = (h n) ===> mass = (2 h n / c2) Momentum =(m c) = (2 h n / c) (h = Planck's constant, n = frequency, c = speed of light)
What else can I help you with?
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.
Does light from a flashlight have mass?
No, light does not have mass. Light is composed of particles called photons, which have no rest mass, but they do have momentum and energy.
What doesn't have mass?
There are three known massless particles. Gauge bosons, gluons, and photons.
Do photons have weight?
No, photons do not have weight. Photons are particles, made pure out of energy, which travel at the speed of sound.
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.
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.
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.
Which atomic particle has no mass?
Photons and neutrinos dont have mass.
Does light from a flashlight have mass?
No, light does not have mass. Light is composed of particles called photons, which have no rest mass, but they do have momentum and energy.
What doesn't have mass?
There are three known massless particles. Gauge bosons, gluons, and photons.
Do photons have weight?
No, photons do not have weight. Photons are particles, made pure out of energy, which travel at the speed of sound.
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.
What are tiny bundles of electromagnetic radiation?
Tiny bundles of electromagnetic radiation are called photons. Photons are the basic unit or particle of light and carry energy and momentum. They have no mass and travel at the speed of light.
Is that true that the more energy of a photon the bigger the mass it possesses?
No, all photons have the same mass. Photons are massless (i.e. zero). All the energy in a photon is in its momentum, but increasing its momentum does not change it speed which is always "the speed of light". All massless particles always move at the speed of light.
Why do gamma rays have no mass at all?
Gamma rays have no mass because they are a form of electromagnetic radiation, which consists of massless particles called photons. Photons, including gamma rays, do not have rest mass, but they do have energy and momentum.
What gives electron their speed?
Photons that are absorbed by the electrons. Speed is changed by an exchange of momentum, which is equal to the mass times velocity (with regards to electrons, at least - photons are massless and their momentum works a bit differently.) Since electrons have such a tiny mass, it doesn't take much to make it go very, very fast.
Does electromagnetic radiation has mass and charge?
Electromagnetic radiation, such as visible light or radio waves, does not have mass since it consists of massless particles called photons. These photons do not have an electric charge either but can carry energy and momentum.
