Last Minute Help PLeasee!!

[meefz]

Hey.
I was having some confusion as to understanding which side will have a force (ie, AB,DC or BC)
and also which side will have a force when the coil is rotated 90 degrees.
help would very much be appreciated.  

[3Xamz]

They will all have a force, because they are all perpendicular to the field lines.
This thing wouldn't work because all the sides (DC, AB etc) will be pushed outwards, and in fact the thing would buckle or even break apart given the current and magnetic field is strong enough.

It sure as hell won't turn smoothly =/

[Chavi]

You have to use the Right hand slap rule in this case. Your fingers are the field, the thumb is the current and your palm points in the direction of the force.
The conventional current flows from the positive terminal of the battery (the longer horizontal line), so Current flows from D to C (or B to A).
Now, with the field, it always aligns in the direction from North Pole to South pole.

Using the Right hand Slap rule, in this case, the force on DC points into the page - so there is no movement in the coil.

If the coil is rotated 90 degrees, then the force will clearly be on sides AB or DC.

(Also note, that the force on sides AD and BC doesn't creates a torque - so you can simply ignore it.)

[m@tty]

A force is experienced by wires which are not parallel to the field. The magnitude of the force is proportional to the amount of the wire which is perpendicular to the field (figured out by constructing a right angled triangle and using trig).

However in VCE we are only required to determine the forces when it is either parallel or perpendicular. When the wire is parallel, the force is zero; when it is perpendicular, the force on a single wire is where B is the magnetic field strength, I is the current through the wire and l is the length of the wire in meters. If there are multiple wires, the force on the wad is equal to where n is the number of wires.

The direction of the force is given by the right hand slap rule (there are others but this is easiest, I think).

Point the fingers of your right hand in the direction of the magnetic field(direction of the field lines, or N to S).

Point your thumb in the direction of the conventional current in the wire - ie. the direction which positive charge is flowing.. or the opposite of where negative charge is going.

The resulting direction which your palm is facing is the direction of the force.

[Chavi]

I love how with every minor query there are heaps of ppl jumping to answer the question. Kudos

[3Xamz]

I love how with every minor query there are heaps of ppl jumping to answer the question. Kudos

VN FTW!

[m@tty]

Yeah, it helps everyone when there are multiple explanations coming from different angles and with different focuses.

And this is my study =P

[3Xamz]

Yeah, it helps everyone when there are multiple explanations coming from different angles and with different focuses.

And this is my study =P

Haha, likewise. It's at a point where reading other people's explanations and trying to put mine into words has become my primary source of studying atm. ><

[xygoninator]

Lulz, Meefa.