particles and waves Flashcards
1
Q
order of magnitude
A
bigger number divided by the smaller number, the number of zero’s left
2
Q
fermions
A
protons and neutrons can be broken down into these smaller sub-atomic particles
3
Q
types of fermions
A
quarks and leptons
4
Q
types of quarks
A
up, down, charm, strange, top, bottom
5
Q
types of leptons
A
electron, electron neutrino, muon, muon neutrino, tau, tau neutrino
6
Q
charge of quarks
A
up, charm, top (2/3) down, strange, bottom (-1/3)
7
Q
charge of leptons
A
electron, muon, tau (-1) neutrinos (0)
8
Q
bosons
A
force carriers
9
Q
types of bosons
A
photon, gluon, z boson, w boson, higgs boson
10
Q
charge of bosons
A
photon, gluon, z boson, higgs boson (0) w boson (+-1)
11
Q
fundamental forces
A
strong nuclear force, weak nuclear force, electromagnetic force, gravity
12
Q
gluon fundamental force
A
strong nuclear force
13
Q
w boson and z boson fundamental force
A
weak nuclear force
14
Q
photon fundamental force
A
electromagnetic force
15
Q
strong nuclear force use
A
holding nucleus together
16
Q
weak nuclear force use
A
fermion decay
17
Q
electromagnetic force use
A
causes like charges to repel and opposites to attract
18
Q
beta decay
A
mediated by the weak force, there are two types: beta+ and beta-
19
Q
beta+
A
produces an antielectron (positron) and a neutrino
20
Q
beta-
A
produces an electron and an antineutrino
21
Q
how was beta decay discovered
A
the law of the conservation of momentum was not being observed
22
Q
neutrinos
A
they have a very small mass and weak interaction with other particles
23
Q
an electric field
A
a region in which an electric charge experiences force
24
Q
arrows on electric field diagrams
A
indicate the direction of force on a positive charge
25
electric field lines
show the direction of a force on a positive charge
26
a uniform electric field
exists between two parallel charge plates
27
when a charge is moved in an electric field...
work is done
28
potential difference symbol
voltage (V)
29
potential difference
the work done in moving one coulomb of charge between the two points in an electric field
30
potential difference units
joule per coulomb (JC^-1)
31
magnetic field
they exist around a current-carrying conductor
32
B
magnetic field
33
I
current (flow of electron)
34
A.C. supply
accelerates particles in one direction and then the other, allows it to go in a circle or a straight line
35
radioisotopes
unstable nuclei
36
nature of alpha
a helium nucleus
37
nature of beta
a fast moving electron
38
nature of gamma
a high frequency EM wave
39
in gamma decay
there is no change in the isotope, only energy is emitted
40
nuclear fission
when a large nucleus splits into two nuclei of smaller mass with the release of several neutrons and energy
41
types of fission
spontaneous (with a fixed half life) or stimulated
42
stimulated fission
when the nucleus is hit by an incident neutron causing it to undergo fission
43
lost mass in fission is converted to...
energy
44
lost mass in fission equation
E=mc^2
45
constructive interference
when a crest meets a crest and a maximum amplitude is produced
46
destructive interference
when a crest meets a trough and the wave length is cancelled out
47
maxima
occurs at points of constructive interference
48
interference pattern
formed by two coherent sources
49
m (central maximum)
0
50
minima
occurs at points of destructive interference
51
d
separation of the slits
52
theta (mxlambda=dsintheta)
the angle between the central maximum and the first fringe
53
central maximum of white light
where all wavelengths interfere constructively
54
other maximums of white light
a spectrum, violet is closest to the central maximum in every spectrum
55
irradiance is defined by...
the power per unit area
56
irradiance units
Wm^-2
57
the relationship between intensity and distance
can be shown to follow an inverse square law (only for a point source)
58
a point source
something that gives light out in all directions
59
refraction
the slowing of light as it passes from a less dense to a more dense optical medium (i.e. air to glass)
60
the absolute refractive index symbol
n
61
the absolute refractive index
the ratio of the speed of light in a vacuum to the speed of light in the material
62
frequency of light in different material
is the same
63
the critical angle
the angle of incidence such that the angle of refraction is 90 degrees
64
angle smaller than the critical angle
will cause light to refract
65
angle bigger than the critical angle
will show total internal reflection
66
electrons can exist in...
different (discrete) energy levels in the atom
67
emission of photons
when atoms are excited their electrons jump to higher energy levels, when they fall back down to their ground state, a photon is emitted
68
the energy of the emitted photon
equal to the energy difference between the two energy levels
69
frequency and wavelength of the photons can be calculated using
E=hf
70
absorption spectra
produced when specific frequencies of photons from white light are absorbed by atoms of hydrogen
71
why is energy released in nuclear reactions
mass lost is converted to energy
72
why is an alternating supply used
particle always accelerates in the same direction
73
mesons
a hadron containing a quark and an antiquark
74
antiparticle
the same magnitude of charge as its particle but opposite sign
75
baryon
comprised of 3 quarks
76
hadron
comprised of of two or more quarks held together by the strong nuclear force, mesons or baryons
77
why are some fusions hard to sustain
they require high temperatures
78
how to improve irradiance experiment
black cloth on desk to reduce reflections
79
coherent
the waves from the two sources have a constant phase relationship
80
shorter wavelength
fringes are closer together
81
for an atom to be ionised
the electron must be in the highest energy level
82
how is the photoelectric effect demonstrated
using a gold leaf electroscope -only negatively charged electrons discharge
83
does dim UV light discharge a gold leaf electroscope
yes, due to its high frequency
84
does white light discharge a gold leaf electroscope
no, due to its lower frequency
85
the photoelectric effect depends on
frequency
86
threshold frequency
below this (fo) there is no photoelectric emission
87
increasing intensity at f
will have no effect
88
increasing intensity at f>fo
will cause more photoelectric emission, they are directly proportional
89
a bigger intensity results in
a bigger photoelectric current produced
90
work function
a minimum energy needed by an electron produce photoelectric emission (escape from a metal)
91
the work function is dependent on
frequency
92
left over energy from the work function is
kinetic energy
93
the emission of beta particles in radioactive decay is evidence for the existence of
neutrinos
94
why do no electrons leave the plate when the frequency of incident radiation is below fo
photons with frequency below fo do not have enough energy to release electrons
95
how are dark lines in spectrum produced from the sun
photons of certain frequencies are absorbed in the suns outer layers
96
two features of the bohr model
a positively charged nucleus, electrons in energy shells
97
why is a spectrum produced from white light in a prism
different colours have different refractive indices
98
how does photoelectric emission prove light acts as particles
each photon contains a fixed amount of energy
99
j
less dispersion
100
why do some colours of LED not work
the electrons do not gain enough energy to move towards the conduction band of the p-type
101
what happens to path difference when the distance separating the gaps increases
nothing as the wavelength hadn’t changed
102
explain why protons are accelerated by an electric field
protons are positively charged so experience a force
103
why would a screen glow brighter if potential difference is now higher
electrons will gain more energy
104
what happens to the pattern with grating with more lines per mm
spots will be further apart as angle is greater
105
a difference in spectrum of a prism with a lower refractive index
less deviation in spectrum position
106
why would a larger split separation produce a less accurate value for wavelength
angle is less so higher percentage uncertainty
107
why do tube lengths increase in a particle accelerator
the speed of the particle increases so they travel further in the same time
108
how would a higher frequency of light refract
a smaller angle since refractive index is greater
