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## Homework Statement

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.

## Homework Equations

## 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.