Notes in 03 Waves

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Status	Last Update	Fields
Published	01/09/2024	progressive waves{{c1::carries energy from one point to another without transferring any material}}
Published	01/09/2024	how is a wave caused{{c1::particles or fields(electric or magnetic fields) ossilate at source}}
Published	01/09/2024	what can happen to waves{{c1::reflected}}{{c1::refracted}}{{c1::diffracted}}
Published	01/09/2024	reflection{{c1::wave bounced back when it hits boundary}}
Published	01/09/2024	refraction{{c1::wave changes speed as it enters different medium -> can result in change in direction}}
Published	01/09/2024	in refraction why does wave change directions{{c1::wave speeds up or slows down -> different optical densities of mediums}}
Published	01/09/2024	diffraction{{c1::wave spreads out as it passes through gap or round an obstacle}}
Published	01/09/2024	displacement of a point on a wave graph{{c1::how far a point has moved from its undisturbed position}}
Published	01/09/2024	what does a negative displacement show{{c1::point on wave has moved below undisturbed position}}
Published	01/09/2024	what does a positive displacement show{{c1::point on wave has moved above undisturbed position}}
Published	01/09/2024	amplitude{{c1::maximum magnitude of the displacement between undisturbed position and crest}}
Published	01/09/2024	wavelength{{c1::length of one whole wave ossilation/wave cycle}}
Published	01/09/2024	wave ossilation/wave cycle{{c1::distance between two crests(or troughs)}}
Published	01/09/2024	period{{c1::time taken for one whole wave cycle to cross a point}}
Published	01/09/2024	wave frequency{{c1::number of whole wave cycles per second passing a give point}}
Published	01/09/2024	phase{{c1::measurement of the position of a certain point along the wave cycleexplanation:- allows us to pinpoint a specific point in a wave by:- vert…
Published	01/09/2024	phase difference{{c1::amount(can be in angles/radiance) by which one wave lags behind another waveNote: Phase difference can be between particles too(…
Published	01/09/2024	phase and phase difference can be measured in {{c1::angles(in degrees or radians) OR fractions of a cycle[see below 2nd image.]note: phase is use…
Published	01/09/2024	formula for frequency(waves){{c1::f = 1 / Tf = freq.T = periodNote: the 1 in the formula basically means in 1 second, T is the time takes for one wave…
Published	01/09/2024	formula for wave speed{{c1::c = d / tc  = wavespeed(ms-1)d = distance(m)t = time(s)}}{{c1::c = f λc = wavespeed(ms-1)f = frequency(Hz)λ = wavelen…
Published	01/09/2024	derivation of wave speed equation{{c1::c  = d / t}}{{c1::c = d / (1 / f)     [since f = 1 / t OR t = 1 / f]}}{{c1::c = λ · f}}
Published	01/09/2024	transverse waves{{c1::displacement/oscillation of particles or fields is perpendicular to propagation of energy//direction of energy transfer}}
Published	01/09/2024	examples of transverse waves{{c1::electromagnetic waves}}{{c1::earthquake shock waves(S-waves)}}{{c1::waves on string}}
Published	01/09/2024	how to draw transverse waves{{c1::displacement distance graph}}{{c1::displacement time graph}}
Published	01/09/2024	what does "+" and "-" displacement show{{c1::displacement upward or downward the centre line}}
Published	01/09/2024	longitudinal waves{{c1::displacement of particles or fields is parallel to direction of energy transfer}}
Published	01/09/2024	examples of longitudinal waves{{c1::sound waves}}{{c1::P waves}}
Published	01/09/2024	44a65a88c0c44f91a082318c8938436c-oa-1
Published	01/09/2024	44a65a88c0c44f91a082318c8938436c-oa-2
Published	01/09/2024	polarised waves{{c1::wave that ossilates in only one direction}}
Published	01/09/2024	what happens if you try to pass waves in a rope through a vertical fence{{c1::fence filters out vibrations that are not vertical}}{{c1::only vertical …
Published	01/09/2024	use of polarising filter{{c1::polarise light and other waves}}
Published	01/09/2024	when does a second polarising filter block out all the light(when placed on top of the first){{c1::transmission axis' of both polarisers are at a righ…
Published	01/09/2024	graph showing light intensity against rotation of second filter from plane of polarisation{{c1::}}
Published	01/09/2024	why does graph have a trough at 90°/270°{{c1::transmission axis of second filter is perpendicular to first - no light gets through}}
Published	01/09/2024	what does polarisation provide evidence for{{c1::nature of transverse waves since polarisation can only happen to transverse waves}}
Published	01/09/2024	application/use of polarisation in the real world{{c1::glare reduction}}{{c1::improving TV and Radio signals}}{{c1::stress analysis of plastics}}
Published	01/09/2024	how to reduce glare using polarisation{{c1::light reflected by surfaces - water/tarmac/glass - partially polarised}}{{c1::using polarising filters, we…
Published	01/09/2024	how does polarising help improve TV and Radio Signals{{c1::to recieve a strong signal, rods on receiving aerial and transmitting aerial should be line…
Published	01/09/2024	who discovered polarisation and how was it discovered?{{c1::Etienne-Louis Malus, 1808}}{{c1::light was polarised by reflection}}
Published	01/09/2024	how was the nature of electromagnetic waves discovered{{c1::discovery of polarisation by reflection}}{{c1::suggestion that light was transverse(vibrat…
Published	01/09/2024	when are two points in phase{{c1::if both are at the same point in the wave cycleWaves have same displacement(if point in same wave)  and velocit…
Published	01/09/2024	360° = {{c1::2π}} radians
Published	01/09/2024	phase difference of two points in the same phase {{c1::zero}}{{c1::multiple of 360° (full cycle)}}
Published	01/09/2024	convert degrees to radians{{c1::multiply π/180°}}
Published	01/09/2024	convert radians to degree {{c1::multiply 180°/π}}
Published	01/09/2024	antiphase{{c1::exactly out of phase/opposite phases}}
Published	01/09/2024	phase difference of particles in antiphase{{c1::180° or π radiance}}
Published	01/09/2024	can waves with different amplitude be in phase{{c1::yes}}
Published	01/09/2024	phase difference symbol{{c1::Φ (phi)}}
Published	01/09/2024	when does superposition happen{{c1::two or more waves pass through each other}}
Published	01/09/2024	principle of super position{{c1::when two or more waves cross, resultant displacement equals the vector sum of individual displacements}}
Published	01/09/2024	interference{{c1::superposition of two or more waves in similar direction}}
Published	01/09/2024	conditions for observable interference{{c1::two sources are coherent}}i.e. {{c1::same wavelength/frequency}} and {{c1::constant phase differ…
Published	01/09/2024	what happens in constructive interference{{c1::if displacements are in same direction, displacements combine to give bigger displacement}}
Published	01/09/2024	what happens in destructive interference{{c1::positive displacement meets a wave with negative displacement → cancel each other out}}
Published	01/09/2024	formula to calculate phase difference between two points on the same wave in radians(or degrees){{c1::θ = d/λ × 2π(or 360°)θ = phase difference in rad…
Published	01/09/2024	types of interference{{c1::constructive}}{{c1::destructive}}
Published	01/09/2024	conditions for constructive interference{{c1::two waves arrive at point in phase}}
Published	01/09/2024	when does destructive interference happen{{c1::wave arrive at a point in anti-phase}}
Published	01/09/2024	path difference{{c1::difference in distance two waves have travelled}}
Published	01/09/2024	conditions for complete destructive interference{{c1::coherent waves}}{{c1::path difference = nλ + 1/2λ = (n + 1/2)λ}}{{c1::therefore, phase differenc…
Published	01/09/2024	8e9842adc8a8451fa9587c5e4814b30d-oa-2
Published	01/09/2024	maxima in interference pattern{{c1::line connecting points where path difference is nλ → displacement is maximum}}
Published	01/09/2024	minima in interference{{c1::line connecting points where path difference is (n + 1/2)λ → indicate displacement is zero}}
Published	01/09/2024	how to find whether constructive or destructive interference happens in diagram:{{c1::}}
Published	01/09/2024	how to know when destructive interference happens{{c1::}}
Published	01/09/2024	supercrest{{c1::crest meets a crest and reinforce each other}}
Published	01/09/2024	supertrough{{c1::trough meets trough and waves reinforce eachother}}
Published	01/09/2024	formula for Young's Double Slit experiment{{c1::W/D = λ/sλ = wavelength of the wave(m)s = distance between slits(m)w = fringe spacing, distance betwee…
Published	01/09/2024	what happens to fringes if monochromatic light is changed from green to red{{c1::wavelength increases → fringe diference increases → less fringes appe…
Published	01/09/2024	what happens to fringes if slit seperation increases{{c1::fringe difference decreses}}
Published	01/09/2024	use of colour filters{{c1::make light monochromatic → same frequency and wavelength}}
Published	01/09/2024	use of narrow slit{{c1::diffracts and concentrate light and make it focus on double slit(so it can be lit up)}}
Published	01/09/2024	use of double slit{{c1::make two sources of light → so it can interfere}}{{c1::path difference to S1 and S2 is fixed produce so light traveling t…
Published	01/09/2024	why do we use lasers in single/double slit experiments{{c1::produce coherent and monochromatic light}}
Published	01/09/2024	what does size of slits affect{{c1::light intensity/fringe intensity on screen}}{{c1::amount of diffraction → number of fringes seen on screen}}
Published	01/09/2024	path difference in constructive interference{{c1::nλ}}
Published	01/09/2024	path difference in destructive interference{{c1::(n + 1/2) λ}}
Published	01/09/2024	what is observed in double slit experiment if we use white light{{c1::bright white central maximum - all colours constructively interfere}}{{c1::conti…
Published	01/09/2024	describe appearance of fringes if white light is used instead of red light{{c1::central bright fringe is white}}{{c1::side fringe are continuous spect…
Published	01/09/2024	speed of electromagnetic wave in vacuum{{c1::3 × 108 ms-1}}
Published	01/09/2024	phase difference of particles in phase{{c1::0° or 360° or 2π radiance}}
Published	01/09/2024	stationary wave{{c1::super position of two progressive waves, with same frequency(or wavelength) and amplitude moving in opposite directions}}
Published	01/09/2024	requirement for stationary wave to form{{c1::progressive waves in opposite direction}}{{c1::same frequency(or wavelength)}}{{c1::same amplitude}}
Published	01/09/2024	what type of waves are stationary waves{{c1::transverse}}
Published	01/09/2024	nodes{{c1::point on wave where amplitude of vibration is zerono displacement at any time}}
Published	01/09/2024	anti-nodes{{c1::points of maximum amplitude on stationary wave}}
Published	01/09/2024	interference at nodes{{c1::total destructive interference ‒ displacements of two waves cancel out}}
Published	01/09/2024	interference at antinodes{{c1::constructive interference ‒ displacement of two waves combine to make bigger displacement}}
Published	01/09/2024	resonant frequencies{{c1::frequencies at which exact number of half wavelengths fit on string}}{{c1::frequency at which oscillator produces an exact n…
Published	01/09/2024	first harmonic in terms of frequency{{c1::stationary wave vibrating at lowest possible resonant frequency ‒ first harmonic}}
Published	01/09/2024	loops in first harmonic{{c1::one}}
Published	01/09/2024	in first harmonic how many wavelengths fit onto string{{c1::half wavelength}}
Published	01/09/2024	loops in second harmonic{{c1::two}}
Published	01/09/2024	in second harmonic how many wavelengths fit onto string{{c1::one wavelength ‒ wavelength is length of string}}
Published	01/09/2024	at nth harmonicantinodes = {{c1::n}}nodes = {{c1::n + 1}}
Published	01/09/2024	at nth harmonic how many wavelengths fit onto screen{{c1::n/2}}
Published	01/09/2024	given first harmonic, how to work out nth harmonic's frequency {{c1::f = n × first harmonic frequency}}
Published	01/09/2024	formation of stationary waves{{c1::progressive waves of same freq. and amplitude travel in opposite direction}}{{c1::reflected waves interfere with in…
Published	01/09/2024	other demonstrations of stationary waves(aside from string){{c1::stationary microwaves}}{{c1::stationary sound waves}}
Published	01/09/2024	how to demostrate stationary waves by microwaves{{c1::set up microwave beam at metal plate}}{{c1::super position of wave and reflections produces stat…
Published	01/09/2024	how to demonstrate stationary waves using sound waves{{c1::loudspeaker produces stationary sound waves in tube}}{{c1::powder laid along bottom is shak…
Published	01/09/2024	how to find speed of sound using{{c1::distance between pile of powder(node) = λ/2}}{{c1::c = f · λ so speed is calculated by measuring d and knowing f…
Published	01/09/2024	diffraction{{c1::waves spread out as they go through narrow gap or around obstacles}}
Published	01/09/2024	amount of diffraction through gap depends on{{c1::wavelength of wave}}{{c1::size of gap}}
Published	01/09/2024	relationship between wavelength and size of gap in diffraction{{c1::gap lot bigger than wavelength → unnoticeable diffraction}}{{c1::gap several wavel…
Published	01/09/2024	ef4176b64f9448d8951ef70c920a68e3-ao-1
Published	01/09/2024	wavefront{{c1::surface through crests which is normal to direction of energy transfer of wave}}
Published	01/09/2024	diffraction around obstacle if obstacle is wider than wavelength{{c1::less diffraction ‒ longer shadow}}
Published	01/09/2024	monochromatic{{c1::light of single wavelength and frequency ‒ single colour}}
Published	01/09/2024	coherent light{{c1::same wavelength, frequency and fixed phase difference}}
Published	01/09/2024	diffraction pattern of monochromatic light source through single slit{{c1::broad intense central maxima double in width to adjacent fringes}}{{c1::bri…
Published	01/09/2024	intensity{{c1::power per unit area}}
Published	01/09/2024	what does increase in intensity of monochromatic light mean{{c1::increase in number of photons per second}}
Published	01/09/2024	diffraction pattern of white light{{c1::bright white central maximum}}{{c1::spectra of colours adjacent}}
Published	01/09/2024	why is continuous spectra of colours observed in diffraction of white light{{c1::different wavelengths are diffracted by different amount}}
Published	01/09/2024	why is central white bright fringe found in the middle when diffracting white light{{c1::all wavelengths of light constructively interfere}}
Published	01/09/2024	effects of increasing slit width in single slit experiments{{c1::decreases amount of diffraction}}{{c1::central maximum is narrower}}{{c1::increase in…
Published	01/09/2024	effects of increasing wavelength in single slit experiments{{c1::wavelength increases amount of diffraction [NOTE: dsinθ = nλ , if λ increases, sinθ i…
Published	01/09/2024	two source interference{{c1::waves from two sources interfere to produce pattern}}
Published	01/09/2024	laser safety precaution{{c1::never shine laser towards person}}{{c1::wearing laser safety goggles}}{{c1::warning signs on display}}{{c1::turn laser of…
Published	01/09/2024	cb9b628b4d14453c902b98ad0ade0085-ao-1
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Published	01/09/2024	3b69e1a4023644fba6902032665f3476-ao-1
Published	01/09/2024	3b69e1a4023644fba6902032665f3476-ao-2
Published	01/09/2024	3b69e1a4023644fba6902032665f3476-ao-3
Published	01/09/2024	3b69e1a4023644fba6902032665f3476-ao-4
Published	01/09/2024	how to measure fringe spacing{{c1::measure across several fringes, divide by number of fringes - 1}}
Published	01/09/2024	why do you need a high ratio of D:s // distance D is much greater than s {{c1::only if D is large enough can the angle θ° be small enough for the…
Published	01/09/2024	difference in central maximum between monochromatic single slit and double slit experiment{{c1::central maxima in single slit is wider(double the widt…
Published	01/09/2024	diffraction grating{{c1::lots of equally spaced slits close together}}
Published	01/09/2024	advantage of diffraction grating pattern{{c1::sharp and clear fringe ‒ accurate measurements}}
Published	01/09/2024	why is pattern by diffraction grating more sharp{{c1::more coherent sources ‒ more beams reinforcing the pattern}}
Published	01/09/2024	5dc5f03158754c70b16bedc0cfcf85e5-oa-1
Published	01/09/2024	5dc5f03158754c70b16bedc0cfcf85e5-oa-2
Published	01/09/2024	zero order line{{c1::line of maximum brightness at centre}}
Published	01/09/2024	diffraction grating equation{{c1::d · sin θ = n · λwhered = slit seperationθ = angle to the normaln = order of maximumλ = wavelength of light source (…
Published	01/09/2024	how to find slit seperation in diffraction grating{{c1::d = width of grating/number of lines within width}}
Published	01/09/2024	high optical density of material{{c1::more light slows down when it enters material}}
Published	01/09/2024	optical density is measured by {{c1::refractive index}}
Published	01/09/2024	absolute refractive index{{c1::ratio of speed of light in vacuum and speed of light in material}}
Published	01/09/2024	formula for refractive index of material{{c1::n... = c/c...where n...= refractive index of substance ...c = speed of light(3·108 ms-1)c... = spee…
Published	01/09/2024	refractive index of air{{c1::1}}
Published	01/09/2024	what attributes of wave changes in refraction{{c1::wavelength}}{{c1::speed}}{{c1::frequency stays the same}}
Published	01/09/2024	how to find refractive index between two materials n1 and n2{{c1::1n2 = c1/c2    or   1n2 = n2 / n1 where c1 = speed of …
Published	01/09/2024	snells law formula{{c1::n1 sinθ1 = n2 sinθ2wheren1 = refractive index of material 1sinθ1 = angle of incidencen2 = refractive index of material 2s…
Published	01/09/2024	what is critical angle{{c1::angle of incidence when the angle of refraction makes 90°}}
Published	01/09/2024	when can critical angle be made{{c1::happens when light is passing from a more optically dense material → less optically dense materialn1 > n2}}
Published	01/09/2024	how to find critical angle{{c1::snells lawn1sinθ1 = n2sinθ2where θ2 = 90°so, sinθ2 OR sin90 = 1∴ n1 sinθ1 = n2 ⇒ sinθ1 = n2/n1}}
Published	01/09/2024	when does TIR occur{{c1::angle of incidence > critical angle}}
Published	01/09/2024	what happens in TIR{{c1::ALL light is reflected backwhere as, in normal refraction, only some light is reflected back}}
Published	01/09/2024	symbol for critical angle{{c1::θc}}
Published	01/09/2024	optical fibres{{c1::long pieces of glass/plastic · carry light signal · long distances · use TIR}}
Published	01/09/2024	what does "step index" optical fibres mean{{c1::higher optical density/refractive index of core}}{{c1:: surrounded by cladding with lower refractive i…
Published	01/09/2024	use of cladding{{c1::protects fibre from scratches → no light escape}}{{c1::low refractive index → allow TIR}}
Published	01/09/2024	800297d9e5414140988d37e45c6c5030-ao-1
Published	01/09/2024	800297d9e5414140988d37e45c6c5030-ao-2
Published	01/09/2024	why is light never lost by refraction in optical fibres{{c1::fibre optic is narrow → light always hits boundary at angle > critical angle}}
Published	01/09/2024	advantages of optical fibre{{c1::carries more information → light has higher frequency}}{{c1::doesn't heat up → no energy lost as heat}}{{c1::no elect…
Published	01/09/2024	signals in optical fibres are degraded by {{c1::absorption}} or {{c1::dispersion}}
Published	01/09/2024	absorption(optical fibre){{c1::some signals energy is absorbed by the material the fibre is made of}}
Published	01/09/2024	result of absorption on signal(optical fibre){{c1::energy loss → amplitude of signal reduced}}
Published	01/09/2024	two types of dispersion which can degrade optical signal{{c1::modal dispersion}}{{c1::material dispersion}}
Published	01/09/2024	both material and modal dispersion cause {{c1::pulse broadening::what affect do they have on signal?}}
Published	01/09/2024	pulse broadening{{c1::recieved signal is broader than initial signal}}{{c1::broaderning pulse overlap eachother → information loss}}
Published	01/09/2024	how is modal dispersion caused{{c1::light entering the optical fibre at different angles}}
Published	01/09/2024	how does modal dispersion cause pulse broadening{{c1::light enters fibre at different angles}}{{c2::light takes different paths down fibre::generalize…
Published	01/09/2024	axial ray{{c1::light ray travels straight down middle of fibre}}
Published	01/09/2024	how can modal dispersion be reduced{{c1::use single-mode fibre → light follows very narrow path → smallest path difference}}
Published	01/09/2024	what is material dispersion caused by {{c1::different wavelenghts of light experience different amount of refraction}}
Published	01/09/2024	how does material dispersion cause pulse broadening{{c1::light of different wavelengths experience different level of refraction}}{{c2::different wave…
Published	01/09/2024	how can material dispersion be reduced{{c1::monochromatic light}}
Published	01/09/2024	how can absorption and dispersion be reduced{{c1::optical fibre repeaters}}
Published	01/09/2024	how do astronomers and chemists use diffraction grating{{c1::astronomer - splitting light from stars → line absorption spectra}}{{c1::chemists - analy…
Published	01/09/2024	how is diffraction grating used in X-ray crystallography{{c1::avg. λ of X-ray is = spacing between atoms in crystaline solids}}{{c1::X-rays diffract →…
Published	01/09/2024	major discoveries using X-ray crystallography was {{c1::the structure of DNA}}
Published	01/09/2024	what does the amount of polarisation off a surface depend on{{c1::angle of incidence}}
Status	Last Update	Fields