Physics - Electromagnetic waves

Electromagnetic waves

• Photons - a particle representing a quantum of light or other electromagnetic radiation. It is emitted by a charged particle , because an electron in a shell moves to a lower energy level.
• Antimatter - for every type of particle there is an antiparticle that :
• Annihilates with the particle, converting the total mass into photons
• Has the same rest mass as the particle
• Has an opposite charge to the particle ( if it has a charge)
• What is rest mass?
• Rest mass is the mass of a particle when it isn't moving
• The mass of a particle increases with speed
• Rest energy; energy locked up in rest mass of a particle

Annihilation

• Occurs when matter and antimatter meet, they destroy each other and convert mass into energy.
• e+ + e- = 2hf
• 2hf - two photons are produced in order to conserve momentum and charge which is not possible with one photon.

Pair production

• A photon (usually gamma photon) converts into its matter and antimatter particle.
• gamma rays = e+ +e-
• hf = 2Eo
• One electron volt is defined as the energy when an electron is moved through a pd of 1V.