Trouble with torque and magnetic flux in a current-carrying coil (2 Viewers)

[Dota55]

I understand them alright, but i'm stuck on this question:

Explain why the torque on a current loop in a magnetic field is zero when the magnetic flux through a coil is at a maximum

Can someone please clarify, i don't know how to answer the question....

 

[namburger]

I understand them alright, but i'm stuck on this question:

Explain why the torque on a current loop in a magnetic field is zero when the magnetic flux through a coil is at a maximum

Can someone please clarify, i don't know how to answer the question....

The magnetic flux is the amount of magnetic fleid lines passing through a given area. In a coil the magnetic flux is maximum when the coil is perpendicular to the magnetic field lines and the magnetic flux is minimum when the coil is parallel.

Using T= nBIA Cos Theta
The magnetic flux is maximum when the coil is perpendicular to the magnetic field lines , therefore theta = 90
Cos 90 =0, Thus Torque = 0

 

[me121]

The magnetic flux is the amount of magnetic fleid lines passing through a given area. In a coil the magnetic flux is maximum when the coil is perpendicular to the magnetic field lines and the magnetic flux is minimum when the coil is parallel.

Using T= nBIA Cos Theta
The magnetic flux is maximum when the coil is perpendicular to the magnetic field lines , therefore theta = 90
Cos 90 =0, Thus Torque = 0

This is correct, however if you don't like maths, you can look at it this way.

"The magnetic flux is the amount of magnetic field lines passing through a given area. In a coil the magnetic flux is maximum when the coil is perpendicular to the magnetic field lines and the magnetic flux is minimum when the coil is parallel."

Now using the right hand push rule, when the magnetic field is normal to the plane of the coil, the force on each side of the coil points to the centre of the axis of the coil, and hence no turning force.

I strongly advice that you draw a diagram.

 

[Laura.Ashley]

torque is opposite the magnetic flux
so when magnetic flux is max (perpendicular) torque is minimum, cos 90=0
but when magnetic flux is min (parrallel) torque is max cos 0=1
if you draw a diagram it helps... when the coil is perpendicular, heaps of lines hit it, therefore magnetic flux max
but when coil is flat, not many lines can hit it, therefore magnectic flux is min!
this also really confusses me.. i have my half yearly exams 2moz and not looking forward to it!!!

 

[wogblogger]

mmm tryn pick the differance in my explanation

1. Magnetic flux is maximum when you have the largest area that is perpendicular to the coils ......
i hear you ask why?
well imagine it the largest area is the one that can fit the most stuff through it at the same time
in this case that stuff is the magnetic field lines

now why does this make the torque zero?
well before you start using any fancy cos this sin that tan u
u need to know what torque is.
torque is a turning force
mathematically it is equal to the the product of the force on the wire and its perpendicular distane from the pivot (the place where the coil is rotating)
in this case since we have the maximum flux there is no perdendicular distane as both the wires are directly above and below the pivot

hope u get it now if u dnt send me a message

 

[Forbidden.]

Use the bike as an analogy.
You practically can't push the pedals when they're not in an upright to make it move.
In the parallel position it's the easiest to push the pedals to start moving the bike.