A magnet is suspended next to a solenoid and is free to rotate. When current flows in the solenoid the magnet aligns so that the S pole faces the solenoid. What is the correct direction of the current in the solenoid, ? or ?? Briefly explain.

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1.) When a particle moves under the influence of a magnetic field, the speed of the particle remains constant. Explain why the magnetic force doesn’t change the speed. Why does this also imply that magnetic fields cannot do work?

We have two solenoids with equal magnetic field at the center. The length of solenoid 1 is L1, number of turns is N1 and the current through it is 11. Solenoid 2 of length L2 is seven times longer than solenoid 1, and the current through it, 12, is 4 times larger than 11. How does N2 compare to N1 for the magnetic field at the center of the solenoid to be equal? O N1 = 7/4 N2 O N1=N2 O N1 = 1/7 N2 N1 = 7 N2 N1= 4/7 N2