Why can you use earths magnetic force as propulsion?

0
Posted

Why can you use earths magnetic force as propulsion?

0

A locally generated magnetic field, when placed in an external magnetic field will indeed exhibit a net force on it. Unfortunately, the force is proportional to the dipole moment of the local field times the *gradient* (spatial derivative) of the external field. Not only is the earth’s magnetic field weak, it varies very slowly with position. So, the net force on your craft is negligible. Note that compasses work due to the *torque* on a dipole due to the earth’s field. The torque is proportional to the external field directly (not just its gradient), but there is no significant net force on the needle – just torque. So, if all you’re concerned with is aligning your craft northward, then it might work. The force on a charged particle in a magnetic field is proportional to its velocity and *perpendicular* to its direction of motion, so it does not increase its speed (just direction).

Related Questions