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A LEVEL PHYSICS > 24 - Particle Physics > Flashcards

24 - Particle Physics Flashcards

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1
Q

Thomsons model for atom

A

Plum pudding model:
atom is a positively charged sphere with negatively charged electrons embedded within

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2
Q

Observations and conclusions of Rutherfords alpha scattering experiment

A

most alpha particles passed straight through showing most of the atom is empty space

some were deflected showing that the nucleus is a dense mass concentrated in the centre

some deflected with angles larger than 90º showing that the nucleus had to be a positive charge

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3
Q

size of atom and nucleus

A

radius of nucleus is about 10^-14m and radius of atom is about 10^-10m (nucleus is about 10^5 smaller than the atom)

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4
Q

how to prove proportionality

A

prove that value of k is the same (constant) for each result

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5
Q

nucleon refers to

A

a proton or neutron

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6
Q

A represents

A

nucleon number

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7
Q

Z represents

A

proton number

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8
Q

isotopes are

A

nuclei of the same element with same number of protons but different number of neutrons

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9
Q

what is one atomic mass unit

A

one twelfth the mass of a carbon-12 atom

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10
Q

mass in atomic mass units equation

A

m=Au
mass = nucleon number x u

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11
Q

nuclear size density equation

A

R=r0 x A^1/3
radius of nucleus = r0 x nucleon number^1/3

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12
Q

assumptions for density and volume

A

nucleons are packed together with little to or no empty space

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13
Q

force holding nucleus together and why needed

A

strong nuclear force as grav force attracting nucleons is not enough to match the electrostatic force repelling nucleons

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14
Q

negative force is an

A

attractive force

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15
Q

nature of strong nuclear force

A

can be attractive and repulsive
has a short range
affects all nucleons
attractive to 3fm and repulsive below 0.5fm (graph)

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16
Q

nature of electrostatic force

A

repulsive force
long range

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17
Q

nature of gravitational force

A

attractive force
long range

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18
Q

what are fundamental particles

A

particles that cant be divided into smaller parts (no internal structure)

e.g. quarks, electrons, neutrinos

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19
Q

antimatter

A

every particle has its corresponding antiparticle which has the same mass but opposite charge (antiparticle represented by bar over letter).

when they meet, they destroy each other in a process called annihilation - mass of particles are turned into pair of high energy photons - cosmic rays

20
Q

antiparticle for electron

A

positron e+

21
Q

fundamental forces in order of strength

A

strong nuclear, electromagnetic, weak nuclear, gravitational

22
Q

fundamental forces - ranges

A

grav and EM - infinite
strong nuclear - 10^-15m
weak nuclear - 10^-18m

23
Q

first categorisation of sub atomic particles

A

HADRONS AND LEPTONS

24
Q

hadrons

A

affected by SNF
e.g. protons neutrons mesons (and antiparticles)
if charged experience EM force
decay with WNF

25
Q

leptons

A

not affected by SNF
e.g. electrons neutrinos muons (and antiparticles)
if charged experience EM force

26
Q

classification of hadrons

A

baryons and mesons

27
Q

baryons

A

particles made of 3 quarks e.g. protons and neutrons

28
Q

mesons

A

particles made of a quark and its anti-quark

29
Q

leptons

A

fundamental particles not made of quarks such as electrons, neutrinos and muons

30
Q

building blocks of all matter are

A

quarks and leptons

31
Q

all quarks

A

up down strange (top charm bottom)

32
Q

up down strange quark charges

A

u = +2/3e
d = -1/3e
s = -1/3e

33
Q

quark baryon numbers

A

all 1/3

34
Q

strangeness for quarks

A

all 0 except for strange (-1)

35
Q

proton quark composition

A

uud

36
Q

neutron quark composition

A

udd

37
Q

beta decay and energy spectrum

A

beta decay has a continuous energy spectrum - kinetic energy of electrons released in beta decay can take any value from a specific range of energies

38
Q

beta plus decay

A

proton decays into neutron

proton > neutron + positron + neutrino

39
Q

beta minus decay

A

neutron decays into proton

neutron > proton + electron + antineutrino

40
Q

neutrinos in beta decay reason

A

conserve mass and energy

41
Q

in beta decay what is conserved?

A

nucleon number, proton number and charge

42
Q

force responsible for beta decay

A

weak nuclear force (short ranged roughly 1millionth the size of the strong force)

43
Q

neutrinos charge

A

0

44
Q

conservations in nuclear reactions > beta decay

A

mass energy charge momentum

spin baryon strangeness and lepton number

45
Q

udd > uud also written as

A

d > u

A LEVEL PHYSICS (21 decks)

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