I'm going to talk about generators.
Now, with generators, there's a couple things you need to know.
First, a generator and a motor are really the same thing. A motor is: you put electricity into it
and in turns because of the motor principle. A generator is:
basically, it's like if I take the motor and I'm going to turn the motor. As a result,
there's a coil moving near a magnet, electricity is going to flow
and I want to know which direction that electricity's flowing. Now,
there's AC current and DC current. I'm not going to get into that.
All I'm going to figure out is at this precise moment,
what's happening, which way is the current going to flow?
So, here I have a generator. It's really like a motor. Remember, a motor is
two magnets with a loop of wire.
It's as simple as one loop instead of a bunch.
But here's a wire and it can rotate clockwise or counterclockwise.
Okay? So, for my generator, for this example,
here's my loop of wire in my motor or generator.
And, I'm going to push it with an applied force.
It's like I'm going to take the handle of--
I put a handle on that generator and I'm going to turn it.
And, I'm going to turn it counterclockwise.
That means basically I'm pushing down on this one
and up on this side of the wire. I'm taking the wire and
I'm going to turn it.
Which way will the electricity flow? In the last video,
I mentioned Lenz's law:
the idea that, if a magnet is moving near a coil,
the magnetic field must be in a direction to make it difficult.
So, if I'm pushing a magnet into a coil, the electricity will flow and it's got to be in a direction that makes it difficult
for me to do that. That's the basic thing you got to remember.
So, when this electricity flows in this generator, it's also going to make it difficult for me to do this.
So, if I'm pushing down this way on the wire,
electricity is going to flow in this and it's going to act like a motor. And,
it's going to act like a motor that's trying to go the other way in order to make it difficult.
So, if I push down here, by applied
forces, down here on the wire,
the wire is going to have electricity flow and push the other way.
So, it's as if the wire is pushing against what I'm doing.
The motor
force is going to try and stop this applied force, making it difficult
making it hard for me to turn that generator.
That extra energy is where the electrical energy comes from.
So, when you're doing this, it's okay
If I'm pushing the force that way in the loop,
the motor principle will be in the other way.
And now, I just use the motor principle to figure out what's going on.
Remember, your thumb
points in the direction of
electricity flow.
If the hand is flat, your fingers point from north to south
--so they point to south--
and your palm's in the direction of
the force.
So, in this case, I have two of those three.
I have the force, the motor force.
I'm pushing down. The motor force is the opposite: it's up.
So, therefore, my palm's up.
My fingers have to point from north to south.
So, this way.
If my palm is up and my fingers are to south,
then my thumb is into the board. That's an X.
The electricity is going to end up flowing that way.
Let's look at this side.
I applied force this way, pushing it counterclockwise.
The generator acts like a motor, trying to do the opposite.
So, I know the motor force is down. My palm must be down,
My fingers
need to point to south. My hand is flat, my fingers point to south.
My palm is down, which way is my thumb pointing?
Out.
The electricity is going in here and out there. I'm turning counterclockwise.
It's going to act like a motor going the other way.
Let's try one more. There's so many combinations, but if we do two, I think that's enough.
I apply a force down.
So, the motor force is going to be up.
So, if the motor force is up, my palm's got to be up,
my fingers need to point to south.
My thumb is pointing out. This is a dot.
Let's look at this side.
I'm applying force. I'm turning this thing counterclockwise.
So, the motor of force, is going to counteract that. It's going to be down.
This is going to act like a motor trying to go that way when it generates electricity.
So, my palm is down, my fingers to south,
palm down, fingers to south. My thumb is into the board.
Electricity in this generator is going to flow that way and that's what we're basically looking for.