-In the figure,two solenoids are in line.The switch S,initially closed,is opened.The polarity of the induced emf in terminals X and Y is:
A)X and Y are at the same potential
B)X is positive and Y is negative
C)Y is positive and X is negative

Question

-In the figure,two solenoids are in line.The switch S,initially closed,is opened.The polarity of the induced emf in terminals X and Y is:
A)X and Y are at the same potential 
B)X is positive and Y is negative 
C)Y is positive and X is negative

Quizplus · Accepted Answer

When the switch is opened, the current in the solenoid decreases. This induces an emf in the solenoid, which causes the polarity of the terminals to change. The polarity of the induced emf is such that the current in the solenoid flows in the opposite direction to the original current. This means that the polarity of the terminals is reversed, so X is now positive and Y is negative.

-In the Figure,two Solenoids Are in Line