A way of determining the direction of the force on a wire carrying a current in a magnetic field The thumb represents the force, the first finger the magnetic field, and the second finger the current
When the switch is closed, current flows around the circuit creating a temporary magnetic field that interacts with the permanent magnetic field to create a force that turns the coil
If you have a magnetic field and current, you get force. If you have force and magnetic field, you can get current - this is the basis of electromagnetic induction
The magnetic field in the region shown inside the dotted square is not uniform because the lines are different spaces apart and they are flowing in the same direction, so they are parallel to each other