 So I've got two cases of the pipe. I've got a pipe where I have my hand over one end I've got a pipe where I don't have my hand of one end So when I've got my hand over one end Then I'm pretty sure that what I'm going to have here is a node All right, I'm not going to have any airflow there And so at the other end of I'm they're going to have an anti node if it's an anti node then the fundamental Standing wave is gonna look like that which would be a quarter of a wavelength The other possibility is that I might have it being a node at the other end In which case what we've got is a Half a wavelength across the length of that pipe thereabouts Okay, so what I do know is that when I take my hand away I get a different sound So I'm pretty sure that what we go to is something with an anti node at the other end So the two possibilities are anti node to anti node because I haven't really changed what's happening at the other end or anti node to node So I'm fairly comfortable with my guess about what's happening at this end I'm fairly comfortable that if I got my hand over it, I should have a node there That's just like holding a guitar string still right and if I'm changing something and I am definitely changing something So I can hear a change that it must be going from closed to open at that point So I'm happy with this side. So the real question is what's happening over on this side? I'm not sure so either it's open and so we're going from that case to this case or It's closed in which case we're going from this case to this case. And so the real question is which of these is happening So in this first case where where we tap the hand we get an anti node Then what's happening is we're going from a quarter of the wavelength Fitting in our tube to half the wavelength fitting in our tube and that means that the wavelength has halved And if we've halved the wavelength So if that goes down by a factor of two then the frequency has to go up by a factor of two So in this case the frequency would double and the other case where the hand that we're tapping is where we got a node Then that case is also changing by a factor of two, but you know, it's going the other way. So in this case we're going from There we've got half the wavelength fitting in the tube To there only a quarter of the wavelength is fitting the tube So in that case the wavelength is doubling and if the wavelength is doubling and the frequency is halving So in both cases we've got a change by an octave because the frequency is either doubling or halving But in one case when we take the hand away the frequency is going up and the other case when we take the hand away The frequency is going down. So let's check to see which one it is. So that's a node So is this gonna be an anti node or a node? So if I go like It definitely went up as I took the hand away and what that means from our analysis It means that the hand that I was banging that place must have been an anti node In other words, I was getting large movements of air exactly where I was hitting it, which makes sense And indeed this kind of anti node tends to happen at the open end and a node tends to happen at the closed end