A massless particle
Why do photons have zero mass?
Photons have no REST mass, because they only exist travelling at the light velocity c . However, they do have a mass m (not a rest one !) given by the equation mc2 = h.nu, and there momentum is mc = h.nu/c as it should be.
Is the mass of a photon zero?
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 will you justify that rest mass of photon is zero?
mass of a photon is due to its momentum. When photon comes to rest velocity becomes zero thus mv=p=0 . Hence rest mass of a photon is zero.
What’s the mass of a photon?
Photons are traditionally said to be massless . This is a figure of speech that physicists use to describe something about how a photon’s particle-like properties are described by the language of special relativity.
Did Einstein prove light has mass?
Light is composed of photons, which have no mass, so therefore light has no mass and can’t weigh anything. ... Actually, what Einstein was proving is that energy and mass could be the same thing — all energy has some form of mass .
Why is light affected by gravity if it has no mass?
It might be surprising to you to hear that gravity can affect light even though light has no mass. ... According to general relativity, gravity is actually caused by a curving of space and time . Since light travels in a straight line through straight spacetime, the curving of spacetime causes light to follow a curved path.
How can a photon have energy but no mass?
Since photons (particles of light) have no mass, they must obey E = pc and therefore get all of their energy from their momentum . ... If a particle has no mass (m = 0) and is at rest (p = 0), then the total energy is zero (E = 0).
Does a photon have relativistic mass?
Photons have no inertial mass and no relativistic mass . Experiments have demonstrated that photons do have momentum, though. Special relativity explains this effect theoretically. Gravity affects photons in a way similar to how it affects matter.
How can a photon have momentum if it has no mass?
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.
Is photon a matter?
A photon is generally considered to be a “particle” of light, but this particle is very special. A photon particle does not have any mass (because you cannot “weigh” light), so it is not considered to be matter .
Does light have rest mass?
The rest mass is the mass of a particle (in our case the photon) as measured by an observer who sees the particle still and with zero speed. ... But according to special relativity, light ALWAYS travels with the light speed c, and is NEVER at rest. And so it has zero REST mass .
Can photons exist at rest?
What is a photon? Show that it has zero rest mass or photons can not exist at rest . ... Hence, a photon has zero rest mass. It shows that photon cannot exist at rest.
What does a photon look like?
A photon just looks like a blink of light from a small point . So, when you see a photon (if your eyes are sensitive enough), you see a blip of light. The “size” of a photon is much weirder since photons aren’t “particles” in the traditional macroscopic sense of the word.
Do photons decay?
Photons could conceivably decay , but new analysis of the cosmic microwave background shows that a visible wavelength photon is stable for at least 1018 years. For a photon to decay, it must have a mass—otherwise there’d be nothing lighter for it to decay into. ...
Does light bend with gravity?
Gravity bends light
Light travels through spacetime, which can be warped and curved—so light should dip and curve in the presence of massive objects. This effect is known as gravitational lensing GLOSSARY gravitational lensingThe bending of light caused by gravity .
