Hi everyone. Welcome back to Cody's lab
So I was working a pump for my chlor-alkali cell and I stumbled across something that I thought I'd share with you guys
So I have here an alkaline battery with two magnets stuck to the end and a pool of liquid mercury
Now watch what happens if I lower this down into the pool of mercury and I'm gonna hold on to it here
Just kinda touching the surface
Look at that. The mercury shoots off that way
Now watch what happens if I let this go
Isn't that lovely?
It's like a little boat, just the motor heads away across the pool of mercury
Love the sound it makes too
And if I take one of the magnets and flip it around you'll see what happens
Now it just spins like this
How about that, oh it got hot
Yeah, I guess it is a direct short, basically
So, let me see if I can explain what's going on here
So, these dots
Represent magnetic field lines coming up out of the paper
So, turning to the side, the field lines would look like this, of course, you know little vector arrows here
I guess these can be little crosses... Now if I shoot an electron
into this, the electron interacts with the magnetic field, causing it to deflect
So the electric field's coming up out of the paper, the electron gets deflected
the direction that my fingers are curling here
And it's always going to be deflected at a right angle to the magnetic field. So what's going to happen is the electron's gonna spiral
until it finally manages to get out of the magnetic field
Incidentally, spiraling electrons create a magnetic field
I explain this a little bit better in another video
One when I actually made the world's first electric motor. I'll put a link down in the description so you guys can go watch that
So now when I take my little device here the
magnet is right there. Let's take it away so we can draw this and the other magnets down here
this is the negative end and this is the positive end of the battery and
as for the magnets
This is the north end of the magnet and this is the south end of the magnet and this magnet over here is actually flipped
So that this is the south and this is the north. So the norths are facing out
So the magnetic field lines are coming out around the magnet just like this
and there are of course symmetrical but for ease of
seeing this I'll draw the
direction of the electrons on the other side here
With a dotted line the electrons are going out
From the negative end but I'll start drawing up here from the positive end
Through the magnet
through the highly conductive
mercury metal
Back around through the other magnet and into the other end of the battery
Electrons, of course, go negative to positive
(I think that's how it works...)
If I'm wrong on that blame Ben Franklin. So, the
electrons are going that way, the magnetic field's going this way,
the electron is going to be wanting to be curved up over here and down over here
so
how I had it in the pool would have been like this
so down here,
up on the other side,
and then,
over here everything's switched.
So it would be opposite that – so it'd be down here, up here, the electron's going the other direction
It depends on the direction of the electron and the direction of the magnetic field which direction they get curved
And as the electrons get curved they drag the mercury with it. So the mercury ends up doing a
spiral
Kind of like this
kind of hard to draw in 2D
But since the mercury can't go in a complete spiral it ends up shooting out in that direction
Over here it shoots out in the same direction except for when I had these magnets flipped
In which case it shot out in the other direction so
Now we essentially have the magnet
shooting the mercury
Away, like a rocket and it's generating some thrust. So you have equal and opposite reaction
As the mercury is being blasted away. It is pushing against
our device
but it's only pushing against the bottom portion here and
so it causes it to rotate and
Since this magnet has flat faces
it kind of acts like a paddle and it's able to kind of walk along and
Actually move along the mercury in the opposite direction you think it should
Just thought that was really cool
We can of course test this by using some round magnets. So let's try putting it in here now
Okay, so it still spins like that. Let's flip one of these over
Center it
You see it's not paddling forward it's just kind of wandering around aimlessly and you still see it spins quite quickly
It's because it is still able to push on the mercury
And this battery of course moves a lot less than the mercury does because the mercury is just so heavy
Holding it in place
Does still shoot it off
And actually let's try putting the battery down farther
Aah, see?
Once it is submerged in the mercury instead of shooting off to one side. The mercury actually is able to continue to rotate
all the way around
For the final test, let's put this device down on some conductive aluminum foil and see if it moves
Nope
It really needs to be the mobile mercury. Hope you enjoyed I'll see you next time
