(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Two conducting loops carry equal currents I in the same direction as shown in the figure. If the current in the upper loop suddenly drops to zero, what will happen to the current in the lower loop according to Lenz’s law?

(a) The current in the lower loop will decrease.

(b) The current in the lower loop will increase.

(c) The current in the lower loop will not change.

(d) The current in the lower loop will also drop to zero.

(e) The current in the lower loop will reverse its direction.

http://img21.imageshack.us/img21/8688/lenzrz5.jpg [Broken]

2. Relevant equations

Lenz's law states "Induced emf resulting from a changing magnetic flux has a polarity that leads to an induced current whose direction is such that the induced magnetic field opposes the original flux change."

3. The attempt at a solution

I know that the answer is (b). I am just trying to figure out why.

Lenz's law is just conservation of energy, so if both currents are going in the same direction, than forces are going upwards? If the top one were removed, wouldn't the force acting on the bottom one decrease? I think I am confusing a bunch of things, but trying to understand how/what to approach this problem.

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# Current and Lenz's Law

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