and
then I have a loop like this and I hold
it up in the rain and I then ask the
question how much what water is going to
go through my loop well it's pretty
clear that there are two factors that
determine how much water will flow
through my loop first of all how strong
is the rain how heavy is the rain how
bigger the droplets and how closely are
less spaced and the second aspect of
that is of course is how big is my loop
what's the area and both contribute to
how much rain or would capture through
the space of my loop the rain represents
the magnetic field strength or the
magnetic flux density

so the heavier
rain represents a stronger magnetic
field strength or a stronger like
magnetic flux density and the area is
obviously s as well so the magnetic flux
is a measurement really of how much rain
I capture or how many magnetic fields
lines I capture within my loop and the
two factors basically both contribute
the density of the lines and the area
and as a result, flux is a product of
magnetic flux density and mag

and the area that is in there now if I turn by a loop in that particular angle there then
the area in terms of the ability to
capture raindrops to zero and so in
In this case, my flux is zero if I were to
hold it at a small angle such as this in
the area from above is certainly larger
than zero but it's smaller than the max
an area that I have here again the
amount of Reiner will capture the following
my analogy will be determined by the smaller area which is certainly a
trigonometric ratio reduction of the inner maximum area that

I already have
so that in essence is magnetic flux so
how does an in a changing flux determine
the actual EMF that's generated so if I
were to start from this particular position you could understand
that if I were to rotate this around
then my flux would start at zero in this
particular point it would crucifix as a
maximum as a graph behind me
demonstrates and then as I continue
around and move in a circle then I would
get a sinusoidal curve starting at zero
reaching to a maximum and back to zero
and then a maximum in the negative
direction and as a result that in
essence is changed is basically the value
of the flux the Faraday's law says
actually,

EMF is proportional to the rate
of change of flux so in this particular
position although the flux is actually
at zero the change of flux is actually
at a maximum, there's a rapid change from
zero flux to some sort of positive flux
and so at this particular position in
the rotation the change of flux is at a
maximum whereas in this particular
position the change of flux is actually
at a minimum even though the flux is
actually large the change of flux is
actually very small
anyway they continue on of course

I get
as the same sinusoidal pattern but as
you can see the actual sine curve or the
the curve is actually 90 degrees out of
phase the previous one simply because
the second curve is a derivative of
the first curve but finally of course
Faraday said that the EMF is equal to
the negative rate of change of flux the
negative is due to them
as law and so the third graph shows that
although he my flux is zero my rate of
change lakhs is maximum because of
lenses law

the EMF is in the negative
direction at that particular point as I
moved into this position the EMF is
obviously zero because the rate of
change of flux is zero and then back in
this position even though my actual iam
flux is zero my rate of change of flux
is a negative value but my EMS is a
negative value and hence the third graph
is there I hope you understand therefore
as I turn this I am actually as a result
producing an alternating card as the EMF
changes every 180 degrees I hope that
makes sense
Thanks

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