Students helping students, join us in improving Bored of Studies by donating and supporting future students!
left of the page cos magnetic field goes from North -> SouthI don't get question (a).
How can you only have the north end of the magnet, so which direction is the magnetic field?
How can I use the right hand push rule without a magnetic field direction?
but why is the south end to the left? How do you know?left of the page cos magnetic field goes from North -> South
idk cos there is nothing on the right of the magnet I guess?but why is the south end to the left? How do you know?
It actually does matter!The fact that there is no south pole in the diagram makes no difference -> whenever you have a single pole present in a diagram it should be automatically assumed that it's opposite pole exists somewhere (it's not possible to have a single pole exist by itself) - they just sometimes don't show it in a question, just accept it Re. how do you figure out direction of field, I understand the confusion because only a single pole is shown, but the wire on the far LHS is close enough for the field to be assumed to being perpendicular to the current. A lot of assumptions I know. But you get used to it with enough practice![]()
"This question wanted you to equate torque of ONE SIDE OF THE COIL ONLY!!"It actually does matter!
This question wanted you to equate torque of ONE SIDE OF THE COIL ONLY!!
It wanted to assume that the magnetic field lines had spread out.
Notes from marking centre for that question
Weaker responses demonstrated some misunderstandings regarding torque and force. Common errors included incorrectly equating torque with force and assuming the magnetic field was constant in the equation τ = nBIAcosθ.
The question says that the mass is placed on side X OR side Y, meaning that it wants you to calculate the torque created by that mass. If the same mass was placed on the other side of the coil, then the torques created by both of the masses would cancel out, and you would have no rotational moment (due to mass on side Y creating a clockwise torque, and a mass on side X would produce an anti-clockwise torque)"This question wanted you to equate torque of ONE SIDE OF THE COIL ONLY!!"
What does that mean? How do we know? How could the question be worded so that it wasn't only on one side.
"It wanted to assume that the magnetic field lines had spread out."
What does this mean?
" Common errors included assuming the magnetic field was constant in the equation τ = nBIAcosθ"
Isn't it? What does this mean?
And if current is moving anti-clockwise in the coil, and the magnetic field direction is left, why is the weight on side X. Shouldn;t it be on side Y?