Thursday, February 15, 2018

electromagnetism - Lenz's law and the motor effect


Diagram Of The Motor Effect


The picture shows the basic motor effect, which can be described with Fleming's left-hand rule. There are two cases of what could be happening however.



Case 1: There is a force applied to a wire such that it moves through a magnetic field, this induces a current to flow (the direction of which can be found using Fleming's left-hand rule)


Case 2: There is a wire which passes through a magnetic field, this wire is carrying a current (in the same direction as induced current from case 1). This current causes a force to act on the wire, this force is in the same direction as that of case 1.


Additionally Lenz's Law states that an induced current will flow in the direction as to oppose the movement which created it.


This is where I am confused, as case 1 produces a current which flows in the same direction as case 2, therefore the force produced by this induced current should also be in the same direction as the force in case 2. But this force is in the same direction as movement, it's not opposing it like Lenz's law says it will.


There is obviously a mistake that I am making somewhere but I can't spot it. Can you please help me figure this out and don't hesitate to ask additional questions if my question doesn't make much sense or is ambiguous.




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