particles and anti particles

Question 1

what are photons

Answer 1

packets of electromagnetic radiation

Question 2

what is visible light

Answer 2

one type of electromagnetic radiation

Question 3

what is the electromagnetic spectrum

Answer 3

a continuous spectrum of all the possible frequencies of electromagnetic radiation

Question 4

how are frequency and wavelength linked

Answer 4

frequency (f) and wavelength (lambda) are linked by f = c/lambda

Question 5

what is the speed of light in a vacuum

Answer 5

3.00 x 10^8 ms^-1

Question 6

how does electromagnetic radiation exist

Answer 6

as photons of energy

Question 7

what does the energy of a photon depend on

Answer 7

the energy of a photon depends on the frequency of the radiation. E = h x f = hc/lambda

Question 8

what does every particle have

Answer 8

each particle has a matching antiparticle with the same mass and rest energy, but with opposite charge

Question 9

what is an antiparticle

Answer 9

a negatively charged particle with the same mass as a proton

Question 10

what is an antineutrino

Answer 10

is the antiparticle of the neutrino

Question 11

what is 1 MeV

Answer 11

1 x 10^6 eV

Question 12

how can you create matter and antimatter

Answer 12

from energy. when energy is converted to mass you get equal amounts of matter and antimatter

Question 13

what is the equivalence of energy and mass

Answer 13

energy can turn into mass and mass can turn into energy

Question 14

what is the rest mass

Answer 14

the energy equivalent of the particles mass, measured in MeV

Question 15

what happens if you fire two protons at each other at high speed

Answer 15

you end up with a lot of energy at the point of impact. this energy might be converted into more particles.

Question 16

what happens if a proton is formed in the collision and what is that called

Answer 16

there will always be an antiproton to go with it. its called pair production

Question 17

where is each particle-antiparticle pair produced

Answer 17

from a single photon

Question 18

what is the form of energy that gets converted into matter and antimatter

Answer 18

its in the form of a photon

Question 19

when does pair production only happen

Answer 19

if one photon has enough energy to produce that much mass - only gamma ray photons have enough energy

Question 20

where does it happen near and why

Answer 20

it tends to happen near a nucleus which helps conserve momentum

Question 21

what pairs do you usually get produced

Answer 21

electron-positron rather than any other pair because they have a relatively low mass

Question 22

what is the minimum energy for a photon to undergo pair production

Answer 22

the total rest energy of the particles produced

Question 23

what is the formula for minimum energy for a photon to undergo pair production

Answer 23

E(min) = h x f(min) = 2E(0) (the E then 0 is just the rest energy)

Question 24

what is the result of a particle meeting an antiparticle

Answer 24

annihilation

Question 25

what happens during annihilation

Answer 25

all the mass of the particle gets converted back into energy

Question 26

how long do antiparticles exist for

Answer 26

usually only for a fraction of a second before annihilation occurs, so you dont get them in ordinary matter

Question 27

what is annihilation between

Answer 27

a particle-antiparticle pair, which both have a rest energy of E.

Question 28

what do both photons need

Answer 28

need to have a minimum energy, E(min), which when added together equals at least 2E for energy to be conserved in this interaction

Question 29

what does 2E equal for annihilation

Answer 29

2E(min) = 2E(0)

Question 30

What does E(min) equal

Answer 30

E(min) = h x f(min) = E