A conductive bar glides frictionless on two horizontal, parallel metal rails that, at one end, have a resistance R = 0.4 Ω connected. The rails are separated from each other by the length l = 1.5 m of the conductive bar, in such a way that a closed conduction path is formed. The entire system is exposed to a constant and homogeneous magnetic field B (x, y, z) = 0.8 (2i + 12 j + 5 k) T. Determine: a) The speed at which the bar must move to produce a current of 0.9 A in the resistor. b) The magnitude of the force Fapp applied by an external agent, necessary to keep this speed constant. c) What is the agent responsible for injecting energy into the resistor? The magnetic field or the external agent? d) What is the mechanical power delivered by the force Fapp?

A conductive bar glides frictionless on two horizontal, parallel metal rails that, at one end, have a resistance R = 0.4 Ω connected. The rails are separated from each other by the length l = 1.5 m of the conductive bar, in such a way that a closed conduction path is formed. The entire system is exposed to a constant and homogeneous magnetic field B (x, y, z) = 0.8 (2i + 12 j + 5 k) T. Determine: a) The speed at which the bar must move to produce a current of 0.9 A in the resistor. b) The magnitude of the force Fapp applied by an external agent, necessary to keep this speed constant. c) What is the agent responsible for injecting energy into the resistor? The magnetic field or the external agent? d) What is the mechanical power delivered by the force Fapp?

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