Hi and welcom back to my youtube channel, in previous video we learn about motor effect.
By the end of this video you should be able to understand what's meant by induced potential and the generator effect.
After you watch this video you should be able to describe
all things that affect the size and direction of the induced potential.
Lets start...
Here we can see wire near magnetic field,
if we move the wire through the magnetic field, like this,
then a potential difference is
induced across the ends of the wire.
But, when the wire stops moving, then the potential difference is lost,
if we move the wire back up through the magnetic field
then we get the potential difference again.
We can notice that the potential difference is now reverse direction
This potential difference effect is called  induced potential.
If we have complete circuit, then, in this circuit we induce a current.
This effect is called generator effect.
Like in wire example, direction of the current changes when the direction of movement changes
and if movement of circuit stops then the current also stops.
Also we can get induced potential or induced current if our circuit is stationary but we move our magnetic field, like shown.
One thing we must remeber is that generator effect
will occur only if wire or circuit passes through the magnetic field...
If wire or circuit moves along magnetic field, like shown,
then we do not get an induced potential difference or current.
Size of the induced potential difference or induced current depends in thre factors.
Induced potential difference or induced current is larger if:
- We use stronger magnetic field
- If we move wire or circuit more frequently
- If we shape our wire or circuit in the form of the coil
(more turns of the coil, greater induced potential and current in the wire or circuit)
In this example, you can see magnet how move in and out from the coil of a wire,
as you can see this also produces an induced current.
as we have seen in past examples, direction of the current changes when the direction of movement of the magnet changes.
Remember that we can also change direction of the induced current if we switch poles of the magnet, like shown.
We have to go through one more thing and this thing is quite tricky.
As we have seen, when we move a magnet into a coil of wire, a current is induced in the wire.
As we already know, induced current create own magnetic field and this magnetic field opposes the movement of the magnet.
Let we explaine this, when we insert the North Pole into the coil that end of the coil also becomes a North Pole,
this repels the magnet (as we know from magnetism, the same poles are repelled),
making it harder to push magnet in the coil.
When we pull out magnet from the coil,
that end of the coil becomes south pole,
this attracts the magnet (as we know from magnetism, opposite poles attract each other),
making it harder to pull it out.
Because the induced current makes it harder to move the magnet, this actually means that we are making work.
We are transfering energy from the movement of the magnet into the movement of the current
If we go back to our diagram,
we can see that if we move the
wire through the magnetic field, like this,
then a potential difference is
induced across the ends of the wire.
How we can determine direction of  induced current?
To determine direction of induced current we can use Fleming's right hand rule
How can we use Fleming's right hand rule,
first place your thumb, first finger and 2nd finger,
in such a way that they are mutually perpendicular to each other,
We have to apply right hand in such a way that your thumb points in the direction of motion of the wire
Your forefinger points in the direction of magnetic field,
then the second finger
gives you the direction of induced current.
So, with Fleming's right hand rule we can determine direction of induced current.
Shown in this example, 2nd finger  points direction of the current
and tumb points direction of movememnt of the wire.
Also you can see how direction of induced current changes when we change movement of the wire
If you like, you can pause a video and try to use Fleming's right hand rule.
If you would be aksed, by someday, to describe electromagnetic induction,
there is no better way than with Faraday’s Law of Induction.
Faraday’s law of induction is a basic law of electromagnetism
that predicts how a magnetic field will interact with an electric circuit to produce an electromotive force (EMF).
The equation for the EMF induced by a change in magnetic flux is:
Where EMF is electromotive force in volts,
N is number of turns of coil,
[FI]  is magnetic flux in WEBER
and T is time in seconds.
So, right now we can conclude that three parameters affect size of electromotive force.
EMF is proportional to magnetic flux density
and number of turns of the coil
and  EMF is inversely proportional to time
(EMF is greatest when the change in time Δt is smallest)
I hope that you now know what is generator effect?
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see you on next video.
