## Finding Wavelength from Diagram | Waves | Physics

okay finding wavelength finding

wavelengths from diagram in exam

sometimes they would give you the

wavelengths in the question straight

away but sometimes they do not give you

the wavelengths but they want you to

find a wavelength from diagram even so

it's very important for you to know how

to find a wavelength from diagram okay

let's see the first case wavelength is

the distance between two successive

crests or trough this is for transverse

wave okay so transverse wave we have

craft and we have trough and wavelength

is the distance between crash or the

distance between trough okay so this one

should be no problems but for long if

you´d in a wave we don't have crash and

trough so so how to find a wavelength

now wavelength is the distance between

two successive compressions so we have

one compressions here and we have the

next compressions here so the distance

between two successive compressions if

the wavelength so wavelength is the

distance between two successive

compressions or rarefactions okay

already factions that so this is the

rarefactions this is another very

factions so distance from two successes

rarefaction is also the wavelength but

usually we will use the compressions to

find our wavelength we seldom use the

rarest factions to find a wavelength

because sometimes it's quite hard to

identify where is the red affections

okay so usually we will use the

compressions to identify our wavelengths

okay so this is another compression so

there's another compressions and this is

not another this is not a very factions

so this is how to find wavelengths from

longitudinal wave long acute in a wave

this one is how to find wavelength from

wavefront diagram so this is called wave

fronts diagram okay so this line it

represent wave fronts and if you see

we're friends you should know that the

wave front actually is representing wave

and usually the the wavefronts is either

representing the crass or the trough

okay so if you see the straight line

like this then you should know okay the

the line representing the crass

okay so we have a wave like this for a

circular wave fronts okay

yeah it's also so almost the same

actually and the wavelength the

wavelength is the distance between two

successive crests so our two successive

wave fronts this is one wavefront is not

a reference and the wavelengths from

this wave friends to this wave friends

okay so this is a wavelength and for the

circular wave this is a wave so that is

how to find a wave friends from sorry

with length wavelengths from a wavefront

diagram so this is where front distance

between two successive wave fronts is

the wavelength so this is a wavelength

and this is a wavelength okay first

example figure above shows the

propagation of a water wave what is the

amplitudes of the wave amplitude is the

maximum displacement from the

equilibrium positions right okay from

this diagram what's the amplitude five

okay yes that's correct okay five huh

okay because the the equilibrium

position is from the center okay and

amplitude is from the equilibrium

positions to the maximum point

so therefore the amplitude a is equal to

10 cm divided by two which is equal to 5

cm the figure above shows the

simulations off along it healed in a

wave by using a slinky spring what is

the wavelength of the wave this is long

as you didn't waver longitude in the

wave and this is the compressions

rarefactions compressions or refractions

and from these compressions to this

compression is 15cm

so what is the wavelength lambda is

wavelength so this is the compressions

is the compressions compressions

compressions and ends former

compressions to another compressions is

one wavelength lambda one lambda

wavelength lambda is wavelength okay

from here we can see that three lambda

is equal to 15 cm right 15 cm is

equivalent to 3 lambda and therefore 1

lambda lambda is wavelength 15 divided

by 3 which is equal to 5 cm from here to

here okay one wavelength to wavelength 3

wavelength and Esquivel equivalent to 15

cm so we're flying is equivalent to 5 cm

okay this one this is a transverse wave

it was wavelengths of these transverse

wave okay now from here to here is one

wavelength one lambda and from here to

here there's another lambda right so we

have 1 lambda 2 lambda so 2 lambda or 2

wavelength equal to 25 cm so lambda

equal to 25 divided by 2 equal to 12.5