waves Flashcards
2 points for progressive wave (2)
- transfers energy from one point to another
- w/o transferring material
2 points for describe motion of particle on transverse wave (2)
- oscillates
- about equilibrium position perpendicular to centre
amplitude wave definition (2)
- MAXIMUM displacement
- from equilibrium position
if wave superpose and knot on one wave becomes motionless where is knot
at node (destructive interference)
what waves are transfers
surface of water/water waves/in ripple tank (1)
rope (1)
slinky clearly qualified as transverse (1)
secondary (‘s’) waves (1)
example use polarising filters and why
polaroid sunglasses reduced glare
or 3D glasses = enhance viewing
3 ways to increase fundamental frequency of string (1)
- increase tension
- tighten string
when talking about path wave always say
returns to equilibrium
for describe nature longtidunal (2)
oscillation PARTICLES parallelo to direction of WAVE travel
is light transverse
yes
is ultrasound transverse
yes (can be longitudinal in fluids) but stick w/ transverse
The sound quality of a portable radio is improved by adjusting the orientation of the aerial.
Which statement is a correct explanation of this improvement?
radio waves from transmitter are polarised
relation sound wavelength and light wavelength
sound wavelength > light wavelength
how does polarisation provide evidence for transverse waves
Polarisation provides evidence for the nature of transverse waves because polarisation can only occur if a wave’s oscillations are perpendicular to its direction of travel (as they are in transverse waves).
for tube when in antiphase wavelengths are at
quietest
6 marker on stationary wave formations
(1) a wave and its reflection / waves travelling in opposite directions
meet / interact / overlap / cross / pass through etc
point (1)
• (2) same wavelength (or frequency)
• (3) node − point of minimum or no disturbance
points (3) may come from a diagram but only if the node is written in full and the y-axis is labelled amplitude or displacement
• (4) antinode − is a point of maximum amplitude
point (4) may come from a diagram but only if the antinode is written in full and the y-axis is labelled amplitude or displacement
• (5) node - two waves (always) cancel / destructive interference / 180° phase difference / in antiphase [out of phase is not enough] (of the two waves at the node) [not peak meets trough]
• (6) antinode − reinforcement / constructive interference occurs / (displacements) in phase
• (7) mention of superposition [not superimpose] of the two waves
• (8) energy is not transferred (along in a standing wave).
what to always say in stationary wave at end fo 6 marker
energy is not transferred along standing wave
what can be said for nodes
180 degree phase difference apart
for stationary wave when superpose always same
same wavelength and freq
if motionless
stationary wave formed (explain process if 3 marker on motionless knot)
how to make second harmonic ( adjust for others) on an instrument (2)
lightly) stop (in centre)
pluck or bow
to increase / decrease fundmental frequency how to derive
from equation
what can be said about the space between 2 adjacent nodes on a stationary wave
particles rope oscillate in phase
for a stationary wave what can be said about particles immediately on either side of node
moving in opposite directions
conditions for stationary wave
same frequency/wavelength not ‘it has same frequency’
moving in opposite directions,
reflected at end of string,
same/similar amplitude
integer no of ½ wavelengths between walls
difference progressive and stationary in energy transfer
progressive wave, energy is transferred through space (1)
stationary wave, energy is not transferred through space (1)
difference progressive stationary in amplitude
each point along wave (1)
has same amplitude for progressive wave
but varies for stationary wave (1)
diff P + S in phase
progressive wave, adjacent points vibrate with different phase (1)
stationary wave, between nodes all particles vibrate in phase
[or there are only two phases] (1)
how are stationary waves produced
superposition (of progressive waves)
incident wave and reflected wave/wave reflected through
180O/waves travelling in opposite directions
same frequency/wavelength
in same medium.
for stationary wave have to say at fixed
END not ends
how to calculate value for speed transverse wave usage signal generator set up
frequency read from signal generator when standing wave produced / use of strobe etc.
measure λ using several loops or full length of string
node → node / each loop = λ / 2
use of c = fλ
sunglasses depend on light
polarised when reflected from surface
comparing motion 2 nodes on stationary string
similar freq amplitude and speed ( or pi radians out of phase)
using larger tensions = __ Frequency
reduce diameter w/ increasing tensions = lower mass per unit length therefore greater frequency
–> every metre has a Lower mass
in tension freq length equation what does relationship between 2 variables depend upon
other variables being constant - if not constant then explain why values may be diff using equation
increase diameter by 2
mass increases by 4 (4 x thicker due to square)
if it asks for steps taken by scientific COMMUNITY
-results published
-method checked repeatable
( community = once published)
safety precautions taken while measuring diffraction grating
- don’t look in laser beam
- avoid possibility reflected laser beam
3 points on why only transverse waves polarised (3)
- displacement vector perpendicular to energy travel (transverse)
- longitudinal parallel
- polarisation restriction displacement vector to 1 plane
why can only specific frequency stationary waves form on wire
as fixed ends have to be nodes
what happens to unpolarised EM wave passing through polariser
intensity reduced ( by exactly 1/2)
3 conditions for stationary wave
Same speed
Moving in opposite directions
same wavelength / same frequency/ similar amplitudes
