according to einstein's mass energy relation
M= m'/root[1-(v^2/c^2)]
Where M is mass of particle when it moves with velocity 'v'
And m' is its initial mass.
When particle moves with velocity of light i.e. When 'v=c' then
M= m'/0 =infinity i.e. Infinite mass
But a photon of light can have velocity of light.
So does this possess infinite mass?!!
no, it has zero rest mass m' so its mass is undefined at any speed.
As you know of course it does have finite energy and momentum.
see Wikipedia:
" .... In empty space, the photon moves at c (the speed of light) and its energy and momentum are related by E = pc, where p is the magnitude of the momentum vector p. This derives from the following relativistic relation, with m = 0:[15]
E^{2}=p^{2} c^{2} + m^{2} c^{4}.
The energy and momentum of a photon depend only on its frequency (ν) or inversely, its wavelength (λ):
E=\hbar\omega=h\nu=\frac{hc}{\lambda}
\boldsymbol{p}=\hbar\boldsymbol{k},
where k is the wave vector (where the wave number k = |k| = 2π/λ), ω = 2πν is the angular frequency, and ħ = h/2π is the reduced Planck constant.[16]
Since p points in the direction of the photon's propagation, the magnitude of the momentum is
p=\hbar k=\frac{h\nu}{c}=\frac{h}{\lambda}. ......"
According to Einstein's theory of relativity, the mass-energy equivalence is given by the equation M = m'/√(1-(v^2/c^2)), where M represents the mass of a particle when it is moving with a velocity of 'v', m' is its initial mass, and c is the speed of light.
When a particle with mass moves at a velocity close to the speed of light (v≈c), the equation shows that its mass approaches infinity. However, this equation applies to particles with rest mass, or invariant mass, which means they have mass even when they are at rest.
Photons, on the other hand, are particles of light that travel at the speed of light. They do not have rest mass, meaning they have no mass even when they are at rest. Therefore, the equation M = m'/√(1-(v^2/c^2)) does not apply to photons.
In the case of photons, their energy is given by the equation E = mc^2, where E represents energy and m represents the relativistic mass of the photon. Since photons travel at the speed of light (v=c), the equation simplifies to E = mc^2. This equation shows that the energy of a photon depends on its frequency, not its mass. Photons do not possess mass, but they do carry energy in the form of electromagnetic radiation.
So, while particles with mass increase in mass as their velocity approaches the speed of light, photons do not possess mass, and therefore, they do not have an infinite mass.