So we have a question
From a physics book that is asking if we have
written
If we have a ring that is placed inside a magnetic field
And it is rotating
This axis, which is passing through the diameter. So the radius of this
The radius of this ring from here to here is three centimeter
three centimeter
The resistance of this ring is
0.025
Ohms
And it is placed inside the magnetic field having
The mattock having its value which is
B is the value of B's just
Just LA so B is these
0.23 Tesla
Okay, so we have a ring
the ring has got a resistance of
0.025, ohms the diameter the the radius of this ring is 3 centimeters while it is placed inside
a
magnetic field
Which is perpendicular
Which is perpendicular to this wing
This one is rotated inside magnetic field as it rotates inside metric field
The the current is induced due to the EMF
Generated inside the ring and the electron does start to move
The direction of the motion of electron will depend on the direction of magnetic field inside this ring
which will always oppose to the external magnetic field, so
the EMF
Generated
Inside this ring is given by
The Faraday's laws the rate of change of flux
passing through the rate of radiative flux passing through the ring, which is given by e and
total number of
Turns inside the ring
So we have only one ring. So the total number of hence the value of n is 1
And while the EMF generated we can write is E
Is simply equal to
DQ
DT
times R
So this is current times the resistance agree, which is simply equal to
Phi by DT now
DT over DT causes the rate is same on both sides so they will cancel out
We have Q times R is
Equal to the flux flux is B times a
So what's the area of this ring the end of this ring is simply the area of this small circle
so the area of this ring is a is equal to
pie
R square
Where the value of r is given is
Which is three centimeter three centimeter, which is equal to
0.03 meters I
Will plug these values here and
solve for Q
But we are looking for the total number of electrons which are flowing inside this ring
So the Q can be written is the total number of charges
is equal to
the electron charge on one electron charge
Multiplied by total number of charges. So Q is e n
so if we solve for
total number of charges n
Then this equation can be written as B
Times pie R
Square
divided by
So the electron the charge on electron one electron is we know one point
Six times ten to the power minus
19 coulomb
Minus nineteen and
Then we have the R which is coming into nominator
R
when it really is given is
0.025
Ohms if you just plug all these values and
Solve for the N what we get is we get the total number of electrons we get is 1 point 6
times
10 to the power of
17
This is the huge number of electrons lot of electrons are passing through any point in this way
