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118 Cards in this Set
- Front
- Back
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which fields do moving charges experience |
magnetic and electric |
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what will a charge particle experience? |
a force |
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what is magnetic induction |
the strength of a magnetic field |
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what is magnetic induction measured in |
tesla |
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what does one tesla equal |
1N of force on 1M of wie carrying 1A of current |
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what is the equation for force on a wire |
F = BILsinθ |
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what is the parallel force on a wire |
zero |
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what does your thumb show you in the right hand rule |
force |
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what does your first finger show you in the right hand rule |
field |
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what does your second finger show you in the right hand rule |
current (electron flow) |
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Why does a current carrying wire experience a force in a magnetic field? |
because of the force on individual charges |
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WHats the equation for force on a single moving charge |
F = qvB |
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what must v be for the force on a single moving charge |
the perpendicular speed |
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when will circular motion result |
when s charged particle is moving perpendicular to the field |
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what is centripetal force provided by |
magnetic force |
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whats the equation for radius in circular motion |
r = (mv)/(qB) |
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whats the symbol for angular frequency |
w |
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when does helical motion occur |
when v is tilted forwards |
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what components are there in helical motion |
perpendicular and parallel |
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whats the perpendicular component in helical motion |
v = sinθ |
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what does the perpendicular component in helical motion cause |
magnetic force |
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what is the parallel component in helical motion |
v = cosθ |
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whats the symbol for pitch |
d |
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whats the equation for pitch |
d = (2 π r) / (tanθ) |
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what are electrons accelerated by |
potential difference |
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what does a magnetic field do to an electron |
deflects it |
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what can you do to make an electron undeviated |
adjust the potential difference |
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name 3 origins of cosmic rays |
supernovae, quasars, galactic nuclei |
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what are cosmic rays |
high energy particles with e-m radiation |
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what do cosmic rays react with |
the high atmosphere |
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what is an electronvolt |
the energy of an electron that has moved between 2 points with a p.d of 1 volt |
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what is an electronvolt a unit of |
energy |
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whats the symbol for magnetic field |
B |
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whats the symbol for distance |
L |
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what is simple harmonic motion |
when an object vibrates about an equilibrium position under the position of an unbalanced force |
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what is simple harmonic motion proportional to |
the objects displacement |
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what is simple harmonic motion directed towards |
the centre |
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what does k stand for |
the system constant |
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whats the symbol for displacement in simple harmonic motion |
y |
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what does a distance time graph for a pendulum look like |
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what does a distance time graph for a spring look like
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whats the equation for displacement if y = 0 when t = 0 |
y = Asinwt |
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whats the equation for displacement if y = A when t = 0 |
y = Acoswt |
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what does A stand for |
amplitude |
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whats the equation for max acceleration |
a = -w^2 A |
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when is the maximum velocity achieved? |
when y = 0 |
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what is total energy |
Ep = Ek |
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what is damping |
energy loss from an oscillating system |
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what happens to the amplitude of a dampened oscillation |
it decays with time |
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what is damping caused by |
friction |
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what is this symbol for Φ |
phase difference |
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what is Φ measured in |
radians |
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what law does the intensity of a wave follow |
inverse square law |
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what are the units for intensity of a wave |
Wm^-2 |
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whats the equation for a travelling wave |
y = Asin2π (ft ± x/λ) |
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is it plus or minus for a wave travelling to the right? |
minus |
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is it plus or minus for a wave travelling to the left? |
plus |
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what is beats |
when you add 2 waves together with the same amplitude and similar frequency |
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what is a node |
a point of minimum amplitude |
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what is an antinode |
a point of maximum amplitude |
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what are stationary waves formed by |
2 identical waves travelling in opposite directions |
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do you use plus or minus for an observer moving away |
minus |
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do you use plus or minus for an observer moving towards |
plus |
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do you use plus or minus for a source moving away |
plus |
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do you use plus or minus for a source moving towards |
minus |
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when does division of amplitude occur |
when light beams are reflected and transmitted |
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when is there a π radians phase shift |
when the refractive index goes from lower to higher |
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when is there no phase shift |
when the refractive index goes from higher to lower |
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why do newtons rings occur |
because of interference between light reflecting off lens and glass |
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why do newtons rings get thinner further from the centre |
because of the increasing gradient |
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what is the centre of newtons rings and why |
A minima because of destructive interference |
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what length should a lens coating be |
a quarter of the wavelength |
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what type of images do untreated lenses give |
poor quality |
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what do coherent waves have |
a constant phase relationship |
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where do coherent waves come from |
the same source |
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when do we get maximum effect with lens coatings |
when we cancel out the middle part of the spectrum - green |
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in this image, which line is brightest and why? |
line T because R1 and R2 interfere destructively |
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what happens to the amplitude of a light beam when it bounces off a lens coating |
it splits |
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why do colours in oil spills occur |
because of light reflecting off the surface of the oil and the surface of the oil and water |
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why do you get a range of colours in oil spills and soap bubbles |
because there is no uniform thickness |
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what is the equation for constructive path difference |
S2Q - S1Q = mλ |
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what is the equation for destructive path difference |
S2Q - S1Q = (m +½)λ |
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why will S1 and S2 not meet in phase if they are in different materials? |
because although the path difference may be zero, the different materials have different refractive indexes |
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what is the equation for optical path difference |
optical path difference = n x geometrical path length |
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whats the equation for phase difference |
phase difference = 2π/λ x optical path difference |
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when will this be seen |
when light from 1 source is refracted at 2 or more points |
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what does superposition state |
the resultant of the interference between 2 waves is the sum of the displacement at each point |
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what is important to remember in superposition |
direction |
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describe how you would order maxima and minima |
______________________________ 3 2 2 1 1 0 0 0 1 1 2 2 3 |
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what does Huygen's theory state |
each point on a wavefront acts as a source of secondary wavelets |
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what two things do points on a wave front do according to Huygen's theory |
define a new wavefront or destroy each other |
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what do polarising filters do |
allow the transmission of light in one direction (plane) only |
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what does adding 2 polarising filters in opposite directions do? |
blocks all light |
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what 2 ways can cause polarisation |
transmission and reflection |
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what does the degree of polarisation change with |
the angle of reflection |
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on which surface does polarisation by reflection occur |
an electrically insulation material |
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at which angle does total polarisation occur |
90° |
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what is the brewster angle |
the angle of incidence at which total polarisation occurs |
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what is the symbol for the brewster angle |
ip |
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what is the equation for the brewster angle |
n2/n1 = tan ip |
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what is black body radiation |
radiation emitted by hot objects |
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what does Rayleigh Jeans law state? |
That the intensity is inversely proportional to the wavelength^4 |
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Does the Rayleigh Jeans law agree with experimental evidence? |
no |
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what is another name for the rayleigh Jeans law? |
the ultraviolet catastrophe |
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what happens when a neatively charged metal surface is irradiated with em radiation? |
photoelectrons are released and the surface discharges |
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what charge must a metal surface have for the photoelectrons to be released |
negative |
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what are the two classical theories related to the photoelectric effect and what actually happens? |
1) bright light would discharge the plate real: bright light has no effect, only UV light 2) there would be a time delay while weak UV rays build up energy to discharge electrons real: there is no delay |
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what is the de broglie thing |
λ = h/p λ = h/mv |
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what is the angular momentum formula for electrons |
mvr = nh/2π |
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What are the 2 factors in the definition of the Bohr model of the atom |
electrons revolve around a positive nucleus only in certain allowed orbits the angular momentum of an electron about the nucleus is quantised |
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What does the Heisenberg theory mean in practice |
that there is a physical limit on accuracy |
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what 2 pairs of values are used in the heisenberg theory |
position and momentum energy and time |
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what is the formula for heisenberg theory |
Δx Δp ≥ h/4π |
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what is the wavefunction |
a formula that provides statistical combination of the possible observations that might be made when the wavefront collapses |
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what is the interference pattern interpreted as |
a probability distribution |
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where does a photon have more chance of being detected when it reaches a screen |
where the pattern has high intensity |
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what happens if you turn on detectors in the electron diffraction experiment |
you see no interference pattern |
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What is simple harmonic motion? |
F=-ky When unbalanced force is directlyproportional, and in the opposite direction todisplacement. |
