A, because the resistance of the conductor bar is ignored, the voltages of the two resistors are equal, which is obtained by the formula p = u2r: p1:p2 = R2: r1. Therefore, A is correct.

B. When the conductor bar moves at a uniform speed, the ampere force is FA = B2L2 VR1R2R1+R2, and the friction force is F. According to the equilibrium condition, f+FA=mgsinθ. What do you know? In θ, Fa < MGS, and the solution is v < mgr1r2sinθ b2l2 (r1+R2). So, B is wrong.

C, according to the functional relationship, the sum of the work done by the conductor bar to overcome the Ampere force and the work done by the friction force is equal to the reduction of the mechanical energy of the conductor bar; So, C is wrong.

D. The conductor bar is subjected to gravity, guide rail supporting force, sliding friction force and ampere force, and the supporting force does not do work. According to the theorem of kinetic energy, the sum of work done by gravity, ampere force and friction force on the conductor bar is equal to the increment of kinetic energy of the conductor bar, while friction force does negative work, so the sum of work done by gravity and ampere force on the conductor bar is greater than the increment of kinetic energy of the conductor bar. Therefore, d is correct.

So choose AD.