Question

Magnetic levitation A metal rod of length w = 15 cm and mass m = 85 grams has metal loops at both ends, which go around two metal poles (see the figure). m = mass of red ------ ------- The rod is in good electrical contact with the poles but can slide freely up and down. The metal poles are connected by wires to a battery, and a current I = 3 amperes flows through the rod. A magnet supplies a large uniform magnetic field in the region of the rod, large enough that you can neglect the magnetic fields due to the 8 ampere current. The large magnetic field is oriented to have the maximum effect. The rod floats at rest h - 2 cm above the table. What is the magnetic field in the region of the rod? Assume +x is to the right, +y is up, and +z is out of the page. B - <0,0,.6941 > Which of the following statements are true? If the conventional current in the bar flowed in the opposite direction (to the left), the bar would still float at rest 2 cm above the table. If the conventional current in the bar were less than 8 A, the bar would fall. The magnetic force on the bar is in the +y direction (upward).

Answer 1

A)

Force, F = mg = BIL

Magnetic field, B = mg/IL

B = (0.085 x 9.8)/(8 x 0.15) = -0.69 T

Vector B = (0, 0, - 0.69) T <<<<< (put negative sign to your answer)

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