Induced current in 2 loops

Thread Starter


Joined Apr 19, 2010
A conducting rod of length l = 35 cm is pulled along two frictionless, parallel conducting rails at a constant speed of 8.00 m/s, as shown. A constant, uniform magnetic field B = 2.50 T is directed vertically into the page. Two resistors, R1 = 2.00 Ω and R2 = 5.00 Ω, are connected between the rails and offer the only significant resistance in the loops.

The rod is allowed to come to rest somewhere between the two resistors, after which the magnetic field begins to steadily increase in strength. Explain what happens to the rod.

I understand by Lenz's Law that since there is an increase in magnetic field into the page, the induced field will point out of the page, but then how would you work out the direction of the current, since you cant use the right hand rule, since the rod is at rest?



Joined Jan 12, 2009
If the rod has come to rest at its equilibrium point between the two resistors then it does not matter whether the magenetic field is increased since the ratio between resistors does not change the location of equilibrium does not change. i.e. the rod stays where it is.