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Direction of the magnetic force question and calculation?
A 0.60m long wire of mass 3.0g lies flat on a table, parallel to the East-West direction. The Earth's magnetic field, of strength 5.3x10-5T, runs perpendicularly to this.
(1)What is the direction of the magnetic force on the wire if the current flows from East to West ?
(2)What is the direction of the magnetic force on the wire if the current flows from West to East?
(3) What is the minimum current that must flow through the wire to lift it?
1 Answer
- az_lenderLv 75 years ago
Earth's magnetic field runs from north to south.
(1) F = qv X B. If current flows westward, the electrons drift eastward, so you have
(-)( i ) X (-j) = +k; the force is upward.
(2) Downward.
(3) F = I L B and F = mg, so
I = mg/(LB), you do the arithmetic! where m = 0.003 kg, g = 9.8 m/s^2, B = 5.3x10^(-5)T and L = 0.60m.
