Karteikarten
Waves - Hello goodbye
Karten in diesem Stapel (48)
- 1What is a progressive waveA wave which carries energy from one place to another without transferring any material
- 2What is a wave caused by and how does it's source lose energySomething making particles or fields oscillate at a source, the oscillations pass through a medium as the waves travel carrying energy with it.
A wave transfers this energy away from the source, so the source loses energy - 3What happens to a wave when it is reflected?The wave is bounced back when it his a boundary
- 4What happens when a wave is refractedThe wave changes direction as it enters a different medium (result of the wave slowing down or speeding up)
- 5What happens when a wave is diffractedThe wave spreads out as it passes through a gap or round an obstacle
- 6What is the displacement of a wave?How far a point on the wave has moved from its undisturbed position. metres.
- 7What is the amplitude of a waveThe maximum magnitude of the displacement. metres.
- 8What is the wavelength of a waveThe length of one whole oscillation/wave cycle(the distance between 2 crests/troughs). Metres.
- 9What is the period of a waveThe time for once whole wave cycle. Seconds.
- 10What is the frequency of a waveThe number of oscillations (wave cycles) passing a given point in a second. Hertz.
- 11What is the phase of a wavea measurement of the position of a certain point along the wave cycle
- 12What is the phase difference of 2 wavesTh amount at which one wave lags behind another. Radians/degrees.
- 13Equation for frequency1/(period)
- 14Equation for wave speedC=d/t where c=wave speed
or
C=f(lamda) - 15How do we derive C=f(lamda) from C=d/t ?C=distance moved(lamda)/Time(1/f)
- 16What speed do ALL electromagnetic waves travel at in a vacuum cleaner3x10^8ms^-1 SO IF U GET A QUESTION IN A VACUUM C WILL BE THIS OK
- 17What are the properties of transverse wavesThe displacement(of particles or field) is at right angles to the direction of energy propagation. They travel as vibrations through magnetic and electric fields
- 18What type of wave are ALL electromagnetic wavesTransverse
- 19What 2 ways can you represent transverse ways on a graph?Displacement/distance and displacement/time
- 20What are properties of longitudinal wavesThe displacement of the particles/field is along the direction of energy propagation. The wave consists of alternate compressions and rarefactions of the medium its travelling through.
- 21What type of wave is soundLongitudinal
- 22What is a polarised waveA wave that oscillates in one direction only
- 23How do polarising filters work?Since light waves are a mixture of different directions of vibration a polarising filter can be used to only transmit vibrations in one direction.
- 24What happens when you have 2 polarising filters at right angles to eachotherNo light will get through, this is only at 90 degrees
- 25How does the angle of the second polariser effect light intensity (graph)
- 26What is super position and when does it happenIt happens when 2 or more waves pass through each other and the displacements combine and then each wave continues on its way
- 27What does the principle of superposition state?That when two or more waves cross the resultant displacement equals the vector sum of the individual displacements
- 28How can a complex wave be separated out mathematically into several sine waves (of different sizes)
- 29Can longitudinal waves be polarised?No
- 30What is interferenceA phenomenon in which two waves superpose to form a resultant wave of greater, lower, or the same amplitude
- 31What is constructive interferenceIf the waves displacements are in the same direction, the displacements combine to give a bigger displacement! trough+trough=2trough crest+crest=2crest
- 32What is destructive interferanceWhen a crest + a trough meet (positive+negative displacement) they will cancel each other out. Trough+crest=Crest-Trough since the displacement of a trough is negative
- 33What is destructive interference?When 2 waves with equal and opposite displacements meet they cancel each other out completely
- 34When are 2 points on a wave in phaseIf they are at the same point in the wave cycle (same displacement)
- 35How can we use angles to decide if two points in a wave are in phase?phase difference of 0 or a phase difference of a multiple of 360 are in phase. Points with a phase difference that is an ODD multiple of 180 are exactly out of phase
- 36How can we use angles to decide if 2 waves are in phase?Same rules apply to for just one wave.
- 37What is a stationary wave?The superposition of two progressive waves with the save frequency/wavelength, and amplitude, moving in opposite directions
- 38What is a difference between stationary and progressive waves?Stationary waves do NOT transmit energy but instead STORE energy
- 39How are stationary waves foredstart: interfere destructively 1/4:constructive 1/2:destructive 2/4: constructive
- 40What are resonant frequenciesThe frequencies at which the number of waves produced cause reflected waves to reinforce each other - it causes a stationary wave where the overall pattern forms oscillating loops. At resonant frequencies the exact number of half wavelengths are present
- 41What are nodes on stationary waves?Points at which displacement is 0
- 42What are antinodes on stationary waves?Points of maximum amplitude.
- 43What interference is present at the node?Total destructive interference
- 44What interference is present at the antinode?Constructive interference
- 45What is the first harmonic?Stationary wave vibrating at its lowest possible frequency, one loop with a node at each end. It is half a wavelength.
- 46What is the second harmonic?Twice the frequency of the first harmonic, 2 loops and a node at the middle and at each end. It is a wavelenth
- 47What is the third harmonic?Thrice the frequency of the first harmonic. 1.5 wavelengths fit the string
- 48—
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- GOD Physics (Waves, Mechanics, and Materials) Karteikarten am Waves - Hello goodbye, erstellt von Sophie Cooper am 08/04/2016.
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- Sophie Cooper
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