What is the net magnetic force on a compass needle?

Question

What is the net magnetic force on a compass needle? And by what mechanism does a compass needle line up with a magnetic field?

Answer 1

Depends on the shape and mass of the needle, and of the friction between the needle and the point where it is attached to the compass case.

Moment = Force X distance from the point where the force is applied to the point of rotation (e.g., the center of the compass needle). Thus a little bit of force acting on a great distance can be offset by a lot of force acting on a short distance.

Moment is what allows a very light person way out on the end of a teeter totter to balance out a heavy person sitting close in to the fulcrum. In equation, that would be f X D = F X d; where f is the light person's weight, F the heavy, D the light person distance on the end of the teeter totter, and d the heavy person in close.

Also, F = ma; so if the mass of the needle is great it would take more magnetic force to get the needle moving than it would take to get a needle of less mass to turn towards magnetic north.

Finally, the degree of friction at the point where the compass needle rotates would also have a bearing on how much force would be needed to swing the needle around. Less friction would require less magnetic force to overcome that friction.

Magnetism both attracts and repels. It attracts when opposite poles from two different magnets are put close to each other and it repels when similar poles are nearby. Convention calls these poles north and south because, back when ships were wood and the sailors were iron, they recognized that magnets like to align themselves more or less in a north-south direction.

I say "more or less" because magnetic north is currently some distance from the North Pole. So, when using a magnetic compass to find true north, corrections have to be put into the equation. Aviators used to have to do that all the time when they flew by magnetic compass. Now they fly by gyro compass and do not need to compensate because gyros can be set to point to true north all the time.

Answer 2

Hi. The net force is tiny. The action that makes the needle move is that the needle tries to find the position that balances the field in the needle with the field of the Earth.

Answer 3

It does not make it magnetic nor have a static can charge. you're mixing up static costs with magnetic homes. in case you bear in mind back in technological know-how, rubbing a rubber or plastic rod with silk or cat's fur made it %. up bits of paper. maximum needles around the homestead might are starting to be magnetized through collapsing magnetic fields from automobiles, home equipment and wall wiring, and the people who believe the Silk tale assumed it became into the silk. incorrect. Static costs ensue on insulated factors not metals. Metals can habit a can charge however as in a truck chain dragging to floor. The can charge can not build on the conductor. yet could be drained away by utilising way of the steel conductor.

Answer 4

3% left of center on a radius of 265 degrees north of GMT.