Question

1. do all the direction of the magnetic forces agree with the right hand rule? why are these directions different when you reverse the currrent?

2. In which orientation of the magnetic field will an upwards force act on the swing and why might it be challenging to observe this force?

3. why does one arrangement of wires for the perpendicular orientation have a strong effect on the needle, while the other has no visible effect?

Thank you

Answer 1

1. No, the magnetic field has to be perpendicular to the direction of current in the desired element.

since F= i(LXB)....cross product......so reversing current means L-->-L, so force is in the opposite direction.

2. when the B field is directed into the page and the current is anti-clockwise, then the force is upward

Because of tension in the rope, and weight this force can be internaly compensated. So it is hard to detect. But if springs are attached , then you can see the compression and tension.

3. when arranged in perpendicular orientation, the two possibilities arise...one where the field generated has the same direction as Earth's magnetic field...then deflection will be strong....other opposing the earth's magnetic field, then deflection will be less