The?direction?of the?force?(aka the?thrust) on a current carrying wire depends on the direction of the current and the direction of the magnetic field
All three will be?perpendicular?to each other
This means that sometimes the force could be into and out of the page (in 3D)
The direction of the force (or thrust) can be worked out by using?Fleming's left-hand rule:
Fleming’s Left-Hand Rule can be used to determine directions of the force, magnetic field and current
Worked Example
Use Fleming’s left-hand rule to show that if the current-carrying wire is placed into the magnetic field between the poles of the magnet, as shown below, there will be a downwards force acting on the wire.
Step 1: Determine the direction of the magnetic field
Start by pointing your?First?Finger in the direction of the (magnetic)?Field.
Step 2: Determine the direction of the current
Now rotate your hand around the first finger so that the seCond finger points in the direction of the?Current
Step 3: Determine the direction of the force
The?THumb will now be pointing in the direction of the?THrust (the force)
Therefore, this will be the direction in which the wire will move
Exam Tip
Remember that the magnetic field is always in the direction from?North?to?South?and current is always in the direction of a?positive?terminal to a?negative?terminal.Feel free to use Fleming's left hand rule in your exam, just don't make it too obvious or distracting for other students!