is it true that a photon has 0 mass but a non-zero momentum?if true, then how?

Answer 1

A PHOTON HAS ZERO REST MASS.
But you will never find one resting!!

A new limit on photon mass, less than 10-51 grams or 7 x 10-19 electron volts, has been established by an experiment in which light is aimed at a sensitive torsion balance; if light had mass, the rotating balance would suffer an additional tiny torque. This represents a 20-fold improvement over previous limits on photon mass.

Photon mass is expected to be zero by most physicists, but this is an assumption which must be checked experimentally. A nonzero mass would make trouble for special relativity, Maxwell's equations, and for Coulomb's inverse-square law for electrical attraction.
_________ __________ _________ __________

Just as a simple proof though , use De broglies dual nature formula:
lambda= h/p
lambda= wavelength
h=plancks constant
p=momentum
Thus a photon of any wavelength has a definite momentum

Answer 2

In Newtonian mechanics, the momentum of a particle is

p = mv

So, you'd think that photons can never have momentum. However, in relativistic mechanics, the momentum of a particle on the other hand is

p = Sqrt ( E^2 - m^2 c^4 ) / c

Since photons have mass = 0, we have

p = E/c = (h v) / c

where h is Planck's constant, v is frequency of light, and c is the speed of light. in Quantum Electrodynamics, photons are gauge bosons mediating the electromagnetic interaction between electrically charged particles, "exchanging" momenta between them, like how gluons mediates strong nuclear force between quarks. Photons are quite capable of imparting particles with momentum, even though photons are massless.

Answer 3

A photon has zero REST mass. Of course they are never at rest. And they do have momentum. The total light pressure on the earth from the sun is in the millions of pounds. How is this so?, answer that question at a fundamental level and you can write your own PH.D. at Caltech.

Answer 4

true indeed. mathematically if u see the relativistic mass variation as a particle moves closer to the speed of light its mass tends to increase hence all the energy that u supply to speed it up goes in mass increase rather than increasing its speed so no body with a definite mass can travel at the speed of light EXCEPT LIGHT itself hence a photon has to be massless.
we know from electrodynamics that electrmagnetic waves carry energy and momentum as they travel this is extended to quantum mechanics since a photon is a packet of energy it carries som momentum=hcrossxk

Answer 5

because an electromagnetic wave can exert a force on
a surface, it must carry momentum.
because an electromagnetic wave can transfer heat to a
body upon which it is incident, it must carry energy.
an electromagnetic wave can also behave as though
it were a collection of particles but because those particles
(photons) travel at the speed of light c, they have no rest mass.
therefore, it is possible for a particle that carries momentum
to have no mass. the amount of momentum p, that a massless
particle carries is related to its energy E by the simple formula
E=pc.

the short answer is that any particle massless or otherwise
can carry momentum if it exerts a force on what it collides with.

Answer 6

Yes, a photon has a zero REST mass. But photons don't sit still and do have energy and relativistic mass when moving, so they also have momentum.

Answer 7

Before the relativistic theory,

Mass of an object was considered to be a constant which will not vary with speed.

After relativistic theory,

Mass of an object increases with its velocity.

The kinetic energy of a body is not 0.5 m v v.

It is (change in mass) x C^2.

However when the velocity of a body is small compared to the velocity of light
this K.E is almost equal to 0.5 m v v.

Photons have no rest mass or rest energy.

As it does move with a speed C, its kinetic energy is change in mass x C^2.

Since we know its energy is h n where n is the frequency,

Change in mass x C^2 = h n, the kinetic energy of photon.

Change in mass = hn / C^2.

Change in momentum = (hn / C^2) x C = hn/ C.
Since its initial mass is zero, its initial momentum is zero.

Therefore change in momentum = final momentum of photon = hn/C.


Increase in energy is accompanied by increase in mass of the body.

9 x 10^16 joule is equivalent to one kilogram of mass.

Answer 8

Yes. For a photon, momentum = frequency * h/c

Answer 9

wavelength lambda = h/p

h = planck's constant

p = momentum

thus p = h/labmda

So for any light of finite wavelength, it will thus have a non zero momentum

Answer 10

It is fals because a massless body have no existance.