（25? As shown in Figure 2 of Minhang District, the distance between metal guide rails is D, and one end is connected with a resistor R. If the magnetic induction intensity of uniform magnetic field is B, the direction is perpendicular to. solution: solution: (1) when the conductor bar cuts the magnetic induction line, the induced electromotive force generated at both ends of the conductor bar is equivalent to the power supply of the closed loop, where R is the external resistance, and the internal resistance of the power supply is ignored. Since B, L and V are perpendicular when the conductor bar cuts the magnetic induction line,

E=Blv

where L E=Bdvsinθ, so E = bdd.

(2) The heating power on the resistor R is the electric power of the resistor R, so

PR = I2r = B2D2V2RSIN2θ

(3) When the conductor moves at a constant speed V, the conductor rod is subjected to a pulling force F and an ampere force F, and the two forces are balanced, that is,

f = f? Ann = bil = b2l2vr

p = Fv = b2l2v2r?

P = b2d2v2rsin2θ

It can also be analyzed from the relationship of energy conversion and conservation. Because the conductor moves at a uniform speed, all the mechanical work done by the tensile force is converted into electric energy and joule heat, so

p machine = p heat = b2d2v2rsin2θ?

a: (1) the current intensity through the resistor is bdvrsin θ;

(2) the heating power on the resistor r is B2d2v2Rsin2θ；;

(3) The mechanical power of tensile force is B2d2v2Rsin2θ．.