# Why is use of the earth's magnetic field not a feasible means of flight?

The people on this forum where so helpful with my last problems that I'm posting again! Here are the two I'm having trouble with:
1) What must be the charge (sign and magnitude) of a 1 g particle for it to remain stationary when placed in a downward-directed electric field of magnitude 530N/C? I know the equation E=F/q, but I'm not sure how to apply it in this case.
2) Why is use of the earth's magnetic field not a feasible means of flight?

Thanks again :)

## Answers and Replies

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For question 1, think about what you are trying to do. I assume you mean that the particle is pulled downward by gravity. How much force does gravity apply to the particle? To remain stationary (be in equilibrium) what must be the net force on the particle? Write an equation like f1 + f2 = 0 and solve for the force you don't know. Then use that answer to calculate what the field must be to provide the upward force and choose the sign of the particle charge that will provide an upward force on the particle.

jimmy p
Gold Member
does the earths magnetic field have that greater effect on us?? i would have thought not otherwise our watches and electrical equipment would be affected. However the field lines are always represented as going out of the earth. hmmm this is quite a conundrum. I would say that the earths magnetic field is not strong enough RELATIVELY to be used for flight.