Particle Physics

Question 1

charge of proton/electron

Answer 1

1.6*10^-19C

ions and nuclei have charge but atoms don’t

Question 2

mass of nucleon

Answer 2

1.67*10^-27kg

Question 3

mass of electron

Answer 3

9.1*10^-31

Question 4

Calculating Specific Charge

Answer 4

charge on particle/mass of particle
(INCLUDING MASS OF ELECTRONS)
(C/kg)

Question 5

4 fundamental forces

Answer 5

Strong Force
Weak Force
Electromagnetic Force
Gravity

Question 6

Strong Force

Answer 6

holds nucleons together
attracts: 0.5-3fm
repels:>0.5fm
exchange particle: gluons

Question 7

Weak Force

Answer 7

responsible for decay to more stable particle
range: 10^-17m
Effects particles with mass(FEMIONS)
Exchange particlw: W+, W-, Z0

Question 8

Electromagnetic force

Answer 8

responsible for most particle interactions
Needs charged particcals
range: infinite
exchange particle: photons

Question 9

gravity

Answer 9

weakest force but is ACCUMILATIVE so greatest overall effect
Affects those with mass
range: infinite
Echange pasrticle: GRAVITONS

Question 10

Alpha Decay

Answer 10

only has 2 or 3 DISCRETE energies
…easy to see momentum is conserved
X –> Y+alpha particle

Question 11

Beta Decay

Answer 11

CONTINUOUS spectrum of energy but all beta particles should have same energy for conservation of momentum
… must be another particle, 2 particles going at different angles so different energy
X –>Y+beta particle+anti neutrino
conservation of lepton number

Question 12

Electron Volt

Answer 12

coulombs*volts

1eV= 1.6*10^19

Question 13

Total particle energy=

Answer 13

rest energy(mc^2)+Ke

Question 14

Anhilation

Answer 14

particle and antiparticle colliding forming 2 photons

to conserve energy and momentum

Question 15

Pair Production

Answer 15

energetic photon can suddenly transform into a particle and its antiparticle

Question 16

detecting pair production

Answer 16

they leave distinct trachs and bend in magnetic field
(track from their ionization path)
in cloud chamber or bubble chamber

Question 17

Everything about Planks Constant

Answer 17

h=6.6* 10^-34Js

E=hf
manipulate equation with c=f(lamda)

Question 18

What are exchange particles

Answer 18

virtual particles, unobservable

larger molecules, shorter the range of force (because they can only exist for smaller amount of time)

Question 19

Why have exchange particles

Answer 19

To conserve energy,momentum and charge

Question 20

Hadrons

Answer 20

Baryons (3 quarks)
Mesons (2 quarks)

Quarks are fundemental
Neutrons unstable outside neucleus

Question 21

Leptons

Answer 21

Electron, muon, neutrinos
All fundamental
Some charged some not

Question 22

What to balance in particle interaction

Answer 22

Energy momentum
Charge
Baryon and lepton number

Question 23

Excitation and Deexcitation

Answer 23

Electrons exist in discrete energy levels so need discrete energy photons to move to higher energy level (create absorption spectrum)

Electrons deexcite and release photon of specific frequency (emissions spectra)

Question 24

Florescent tubes

Answer 24

1) voltage accelerates electrons
2) Mercury vapour excited, and deexcire to release UV rays
3) phosphorous coating excited by UV then deexcites releasing visible light

Question 25

Why are florescent tubes at low pressure

Answer 25

Allows electrons to accelerate enough, less collisions with atoms so more likely to have enough energy

Question 26

Electron diffraction

Answer 26

Forms concentric rings

Diffracrs around “slits” of atom spacing in crystals

Question 27

De Broglie Wavelength

Answer 27

Wavelength=h/p

p=mv