Electromagnetic induction and Ampere force A metal conductor connected to an external power supply cuts the magnetic induction line at a certain initial speed in the magnetic field. How will the current through it change?

Look at the power wiring direction, power voltage, conductor movement speed! First of all, when the generated current and power current arrive, it will promote, on the contrary, it will resist. When the generated voltage exceeds the power voltage, on the contrary, it will press the generated current direction. The initial speed has nothing to do with the power supply, but has something to do with the speed. Only tell the initial speed, accelerate!

Does ampere force do negative work in electromagnetic induction? Why?

We must do negative work
Otherwise, it is not in accordance with the conservation of energy
For example, if the conductor rod falls, gravity does positive work, and if ampere force does positive work
The object not only gains more kinetic energy than a free falling body
The circuit also obtains electric energy, which is not conserved

As shown in the figure, a copper bar is suspended by two identical spring scales. There is a uniform magnetic field perpendicular to the paper surface within the dotted line frame where the copper bar is located, and a current from left to right is introduced into the bar. When the bar is stationary, the indication of the two spring scales is F1; if the current in the bar is reversed, when the bar is stationary, the indication of the two spring scales is F2, and F2 > F1. According to the above information, we can determine ( 　）
A. The direction of the magnetic field is perpendicular to the paper inward B. the direction of the magnetic field is perpendicular to the paper outward C. the direction of the magnetic field is perpendicular to the paper upward D. the direction of the magnetic field is perpendicular to the paper downward

Because when the current is reversed, the reading of the spring scale is F2 > F1, so we can know that when the current is from left to right, the direction of the magnetic field force on the conductor bar is upward. According to the left-hand rule, we can determine that the direction of the magnetic field is perpendicular to the paper surface and inward, so a is correct and BCD is wrong

What is the relationship between the work done by the ampere force on the conductor rod, the electric work of the induced current generated by the conductor rod, and the Joule heat of the conductor rod?

In general, these three problems are discussed separately, without quantitative relationship. But they can be arranged in one topic. For example, the guide rail is placed horizontally, and the resistance is ignored. The left end is connected with resistance R. a conductor bar resistance is also r. the guide rail is placed vertically, where there is a vertical uniform magnetic field B. the conductor bar acts under the external force F

Electromagnetic induction and Ampere force A metal conductor connected to an external power supply cuts the magnetic induction line at a certain initial speed in the magnetic field. How will the current through it change?