In the figure,two solenoids are side by side.The switch S,initially open,is closed.The induced current through the resistor R is
A) from a to b.
B) from b to a.
C) There is no induced current through the resistor.

Question

In the figure,two solenoids are side by side.The switch S,initially open,is closed.The induced current through the resistor R is 
A) from a to b. 
B) from b to a. 
C) There is no induced current through the resistor.

Quizplus · Accepted Answer

When the switch S is closed, a current is induced in the left solenoid which produces a magnetic field directed downwards through the right solenoid. This changing magnetic field induces an EMF in the right solenoid, which causes a current to flow in the same direction as the induced magnetic field (i.e. counterclockwise when looking from b to a). This current produces a voltage drop across the resistor R, which causes a current to flow from b to a. Therefore, the induced current through the resistor R is from b to a.

In the Figure,two Solenoids Are Side by Side