Magnetic flux and torque question (1 Viewer)

[weirddivine]

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

 

[untouchablecuz]

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

maximum flux through a coil occurs when the angle between the B field and the coil is 90 degrees. this is because at this point, maximum abmount of flux lines are penetrating the coil

at this point however, the perpendicular distance from the coil to the axis of rotation is 0

so by T=Fd, T=0 since d=0

 

[MrMMMan]

yes, the force on each arm of the coil has no component perpendicular to the plane of coil, so the torque is zero

 

[study-freak]

maximum flux through a coil occurs when the angle between the B field and the coil is 90 degrees. this is because at this point, maximum abmount of flux lines are penetrating the coil

at this point however, the perpendicular distance from the coil to the axis of rotation is 0

so by T=Fd, T=0 since d=0

A correction:
the perpendicular distance between the line of action of the force and the axis of rotation is zero.

 

[Dx_God]

alternatively u can just use the formula. when magnetic flux is at a max (field lines r directly perpendicular 2 the area of the armature) it is 90 degrees to the magnetic field. now u can just sub T=nBIAcosq and it should give u 0. this way its easy 2 understand and explain and easy marks. (though i would probably write everything through all the theories behind but tats obviously 2 hard 4 u 2 understand)

 

[shady145]

and cant u say its related to the change in magnetic flux, when 90* change in magnetic flux is 0 therefore no torque, and at 0* it has the greatest change in magnetic flux hence greater torque <------ this is what my physics teacher told me and never said anything about waqt study freak and untouchablecuz said (from memory)

 

[tian1chen]

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


magnetic flux depends upon the amount of flux lines going through a coil, while the torque is the force experienced by the coil that's all (not exactly, but we can say this for motor coil), real definition is the force times perpendicular distance.
So that aside we can say as a coil reaches maximum flux the turning force (torque) comes to zero as the formula will give more mathematical reasons.


JUST EXPLAINS THE FORMULA OF TORQUE IN HSC (motor)
And here comes the bloody hard part due to the fact that there are TWO sides experiencing a force is a electric motor one up and the other down. It means there are two force however we want the turnnnnning force this means that the direction does not matter which means that there are TWO F=BILsin one for up and the other for down. This then since torque is force times perpendicular distance we times the force by guess what the width of our wire which means that one halve will recieve width/2 and the other witdth/2. This put together means we get TORQUE = 2 * BIL SIN (90 - angle)* width/2 which turns out to be TORQUE = BIACOS(angle) (soz if you aren't good at trigonometry).
A= LENGTH * WIDTH.
If you are fuzz why we use the anlge (90 - angle) it is one angle is positive direction the other negative, but we want it in relation to one angle so it is express like that bitch.

 

[bobos2]

I had exactly the same question.

Use the Right Hand Palm Rule on the two parts of the wire that are affected ( ie, the ones perpendicular to the magnetic field) and you will find that the forces are equal and opposite, and thus cancel out. Consequently, because Torque = Force x Radius, since the Force is 0, then Torque = 0. Therefore, there is no Torque.