The two solenoids in the figure are coaxial and fairly close to each other.
While the resistance of the variable resistor in the left-hand solenoid is increased at a constant rate, the induced current through the resistor R will
A - flow from a to b.
B - flow from b to a.
C - be zero because the rate is constant.
The Attempt at a Solution
I recall something about Lenz Law stating if the current is constant there will be no induced emf, so C is not correct.
If the current is increasing the emf is opposite to I. If the current is decreasing the emf is in same direction as I.
I cannot find anything in my book about this variable rersistor and am having a hard time with this right hand rule for induced current.
If someone can please help me derive at this answer I will greatly appreciate it.