## LESSON 11 - PULSE AT FREE AND FIXED ENDS BOUNDARY

this lesson is about post reflection from fixed and free ends learning

objectives compare and contrast a single post reflection from a fixed and lose

ends use animation to explain the shape of a reflected post at the boundary

identify interferences between two pulses traveling in the same median in

practice pulse interference using pH 18 wave on a string visual web let us

consider what happens to a post when it reaches the end of the median the median

can be fixed like a rope tied to a wall or it can be free like a rope tied

loosely to a pole when the end of the medium is fixed this pulse will reflect

from the free end inverted when the end of the median is free this pulse will

reflect from the free end but not inverted the fix and three ends are

examples of boundary conditions the shape of a reflected pulse for a fixed

and end for a free end of boundary conditions is affected by chill and

detected pulses they are reflected pulse the propagates through the median and

the undisturbed posts isn't East I'll explain this using this online

behavior of a post when hits a boundary for two situations a free end and a

fixed and I will explain the results of this animation in terms of wave

interference a post is half of a wave sometimes is useful to use a pose

instead of a complete wave to observe waves properties to keep simple let me

explain parts of this animation in practical ways for a better

understanding this pink line is a string with one end attached to a boundary for

two ways one is a fixed end and the other one is a free end like the string

attached to a ring around a pole and free to move let me start by selecting

the fix and and around this animation

this is the incident pulse moving to the right and this is the reflected pulse

moving to the left we notice the reflected pulse restore its shapes after

hits the boundary and bounce back to the median with the same shape and with the

same speed but invert it to understand this behavior let's select the box to

show they are reflected incident pulse and as you notice this pulse is being

transmitted to the median now let's check the box show undisturbed reflected

this blue one it shows their own reflected posts the blue overlapping

with the transmitted force which is the red as they meet the boundary during

this overlapping destructive interference of course then as both

pulses move away the reflected pulse is restored and returns to the median

imported now let's uncheck all these boxes select the free end reset this

animation and run one more time we observe the incident posts amplitudes

double IDI hits the boundary then restored to its original amplitude and

returns to the median to understand this behavior let's again select the box to

show a reflected incident posts we notice the wave is me transmitted to the

median now let me check the box show undisturbed reflected posts

it shows the blue posts overlapping with the red posts both waves overlap here at

the boundary here occurs constructive interference as a result of the incident

post amplitude is double and as the blue and red pulses move away the amplitude

is restore to its original shape the also returns to the media in

conclusion for the fixed end and the boundary comes destructive interference

occurs in the reflected pulse Ritu restores its original size as it returns

to the medium averted for the free end constructor interference occurs at the

boundary and the reflected pulse restored should it's normal amplitude

have returned to the medium now then two pulses pass through the same median at

the same time they interact the resulting pulse is obtained by using

constructive interference or destructive interference the issue is also called

superposition after pulses pass through each other each pulse continues along

its original direction of travel and the original amplitudes remain unchanged the

next video I will do a practice pulse interference using pH ET wave on a

string visual level there is wave on a string simulation we are using fixed in

loose ends subserve constructive and destructive interference between two

pulses traveling for the same medium in this case a string to conduct this

practice select pulse for amplitude is light up to 1.25 for pulse width select

0.25 seconds non damping high tension these settings

provide a better view of this interaction first let's observe the

behavior of a single pose traveling through this string notice

this end is fixed at the post generator and at this end

I can select fixed or lose and click on these green buttons and create a posts

let's run with a normal speed now let's select a slow-motion let's stop and use

the time frame to observe with more detail how the post is traveling this is

great review interference with more details click on restart and select lose

and create a post and let's observe in slow-motion so watch the video post in

this lesson post a reflection free and fix ends to understand the shape of

these reflected posts so let's click on restart now let's select fix and and

create two consecutive pulses and observe in slow motion its interference

one two

so we notice sections of destructive interference so for a closer look

let's use the time frame to observe the sequence how it of course let's select a

timer and let's recall the time it takes for five destructive interference occurs

in this case one two three four five so about five point six to seven seconds

takes for five destructive interference of course

so now let's restart and select loose and reset the timer and the create show

pulses and observe its interference one two so we can observe

destructive and constructive interference

this is constructive interference

destructive interference here and

constructive interference so we have positive constructive interference on

the positive side negative constructive interference and that we have

destructive interference so we can to make a sample we can count the time it

takes for five interference of course

one two three four five in conclusion you can use this animation to create two

pulses for one of those two situation fix or lose ends and observe wave

interference constructive and destructive interference