What is difference between photon , electron & positron?

Question

What is difference between photon , electron & positron?

Answer 1

Photon is a 'particle' of light (more correctly, radiation) and it is massless. I use quotes because it is also a wave of electromagnetic energy.

Electron is a negatively charged particle that one of the three major subatomic particles.

Positron is, in very layman terms, a positively charged particle extremely similar to an electron but only exists in antimatter.

Answer 2

Max Plank  (1900) proposed a theory called Plank’s Quantum Theory of  Radiation. According to the theory energy is absorbed or emitted by body, discontinuously, in the form of small packets, each packet of energy is called a  quantum and in case of light, the quantum of energy is called photon. Thus photon can be described as minute energy packet of electro magnetic radiation. The energy of photon depends upon the frequency of radiation  and the two are related as E=hf, where h is known as Plank’s constant, its value is 6.625X10^-34jsec. Photons have no electric charge or rest mass and are the carriers of the electro magnetic field.

Electron was identified in 1897 by J.J.Thomson  and is the first subatomic particle discovered, it is the lightest electrically charged subatomic particle. It carries negative charge(1.602X10^-19 C) an electron has a small mass(9.10953X10^-31Kg) less than 0.1% the mass off an atom.

Now lets come to positron.

History:

The history of antimatter begins with a young physicist named Paul Dirac and the strange implications of a mathematical equation...

It was the beginning of the 20th century, an exciting time when the very foundations of physics were shaken by the appearance of two important new theories: relativity and quantum mechanics.

In 1905 Albert Einstein unveiled his theory of Special Relativity, explaining the relationship between space and time, and between energy and mass in his famous equation E=mc2. Meanwhile experiments had revealed that light sometimes behaved as a wave, but other times behaved as if it were a stream of tiny particles. Max Planck proposed that each light wave must come in a little packet, which he called a "quantum": this way light was not just a wave or just a particle, but a bit of both.

By the 1920s, physicists were trying to apply the same concept to the atom and its constituents, and by the end of the decade Erwin Schrodinger and Werner Heisenberg had invented the new quantum theory of physics. The only problem now was that quantum theory was not relativistic - meaning the quantum description worked only for particles moving slowly, and not for those at high (or "relativistic") velocity, close to the speed of light.

In 1928, Paul Dirac solved the problem: he wrote down an equation, which combined quantum theory and special relativity, to describe the behaviour of the electron. Dirac's equation won him a Nobel Prize in 1933, but also posed another problem: just as the equation x2=4 can have two possible solutions (x=2 OR x=-2), so Dirac's equation could have two solutions, one for an electron with positive energy, and one for an electron with negative energy. But in classical physics (and common sense!), the energy of a particle must always be a positive number!

Dirac interpreted this to mean that for every particle that exists there is a corresponding antiparticle, exactly matching the particle but with opposite charge. For the electron, for instance, there should be an "antielectron" identical in every way but with a positive electric charge. In his Nobel Lecture, Dirac speculated on the existence of a completely new Universe made out of antimatter!

Experimental proof.

In 1932 Carl Anderson, a young professor at the California Institute of Technology, was studying showers of cosmic particles in a cloud chamber and saw a track left by "something positively charged, and with the same mass as an electron". After nearly one year of effort and observation, he decided the tracks were actually antielectrons, each produced alongside an electron from the impact of cosmic rays in the cloud chamber. He called the antielectron a "positron", for its positive charge. Confirmed soon after by Occhialini and Blackett, the discovery gave Anderson the Nobel Prize in 1936 and proved the existence of antiparticles as predicted by Dirac.

First, in the 1960s, came the electron-positron collider. After Anderson's discovery of the positron, physicists soon learned how to create large quantities of positrons (the interaction of radiation with matter can produce an electron and positron simultaneously). Several colliders were built in Europe and the USA, and with them came many important discoveries about the fundamental nature of matter and our universe.

Thus positrons(antielectrons) can be described as subatomic particle having the same mass as that of an electron ,but with an positive charge

Answer 3

Experiment:

With reference to conservation of momentum

Two photon's traveling in opposite directions collide.

Each photon has: 0.511 MeV "at least"

Total energy of photon's = 0.511*2 = 1.022 Mev

Result:

An electron (-e charge) with total energy= 0.511 MeV is created

An positron (+e charge) with total energy= 0.511 MeV is created

Total energy needed for pair of charges = 0.511*2 = 1.022 Mev

Answer: They all have the same energy, but the electron

and positron have charge.