Standing waves

-two waves travelling in opposite directions interfere

-constructive interference if in phase and destructive if anti

-nodes are formed from points of destructive interference

-anti nodes at constructive

-nodes are points of min amplitude and antinodes are points of max

sound waves travel as a longitudinal wave

with oscillations of air particles parallel to the direction of energy transfer

percentage uncertainty

half range of values/mean x100

v=fλ

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v=fλ L=λ/2

2L=λ

2 × 0.45=0.90

v/f =λ

160/0.90= 178

increase tension so increase wave speed

v=√T/μ

since v=fλ and wavelength is unchanged this increases frequency

use a pulley and a set of weights

tension = weight (mg)

the progressive waves are reflected and two waves travelling in opposite directions meet

interference takes place

when the waves are in phase its constructive and they form antinodes

(-opposite for destructive)

-antinodes are points of maximum amplitude so water will not remain at antinodes

-nodes are points of zero displacement so water can stay at theses points

-light is an electromagnetic wave

-oscillations are perpendicular to direction of energy transfer

polarised light

where light oscillates in a single direction

which is perpendicular to direction of travel

at 180 screen is normal

when oscillations are are parallel to the filter no light is absorbed

at 270 screen is dark

gradual change as filter is rotated

as light from screen is partially polarised

the angle of polarisation of filters are 90 degrees to each other

if plane of polarisation of light is not rotated by 90 when it passes through the crystal it can still pass through the upper filter

longitudinal wave

creates compressions and refractions

molecules close together create higher pressures

light from the source is unpolarised

intensity is reduced by ½ by filter 1 by absorbing the perpendicular components

At 180 filter 2 aligns with filter 1 so all light through filter 1 passes through filter 2

As filter 2 is rotated only the component of light of the light from filter 1 in plane of filter 2 is allowed through so intensity reduces

at 90 all light is absorbed because their planes of polarisation are at right angles

-a standing wave is set up in tube

-at constructive interference occurs forming anti nodes and amplitude is at maximum

-at destructive interference opposite

-sand is displaced from points of max amplitude to points of min amplitude

-measure over at least 3 heaps

-divide by number of gaps between the heaps

-repeat measurements and calculate average

d=λ/2

v=fλ

331.5

interference of soundwaves occurs in tubes

nodes and antinodes are formed

anti nodes form when constructive interference and amplitude will be maximum

nodes when destructive and amplitude will be minimum

powder is displaced from points of max amplitude to min amplitude

L=λ/2 v=fλ

344

max velocity of aluminium bat greater than wood

because aluminium is more elastic compared to wood

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p=m/v

1.09 × 10-3

L=λ/2

v=λ f

v=√T/μ

142

initially waves are in phase

as one detector moves there’s a phase difference

there in antiphase at point shown because detector has moved half a wavelength

wavelength = distance/9

v=λf

329

rotate filter / laptop

brightness of screen goes bright to dark every 90

when screen go dark plane of polarised light is polarised light is perpendicular to the plane of polarisation of the filter

2 waves

2T=0.05

T=0.025

F=40

v=λf

λ=7.5

v=√T/μ

v=fλ

320

v=λf L=λ/2

(0.50/5)=λ/2

=360

stress = F/A

strain=Δx/x

YM = stress/strain

stress/YM=strain

0.053

period of oscillation

=T

T=λ/v

T=λ/v

λ=2L

T=5.9

-wavelength same in each string

-thicker string means greater mass

-decreases wavespeed as v=√(T/μ)

-so frequency decreases as v=f/λ

vibrating string causes air molecules to oscillate

molecules are displaced from their positions

when are molecules are colse pressure is high