Question

An iron rod is inserted in a solenoid coil as shown in the above diagram. Find out the correct statements which describes the quantities induced into the iron core when $S{W}_1$ is closed?

• A. Lines of force emanate from side $y$
• B. Lines of force emanate from side $x$
• C. Side $y$ becomes a south magnetic pole
• D. Side $x$ becomes a north magnetic pole
• E. The electric field cancels the magnetic field

Answer 1

The correct option is B Lines of force emanate from side $x$

When switch $S{W}_1$ is closed, solenoid will become a magnet, as we see that current is entering in the wire (solenoid) from side $y$.If we look at side $y$ in front of its cross section , we will find that the direction of current in wire is clockwise.Clockwise means $y$ side is the south $\left(S\right)$ pole of solenoid that's why lines of force enters from this side and emanate from other side $x$.