Question

A circuit contains a battery, a variable resistor and a solenoid. The figure below shows the magnetic field pattern produced by the current in the solenoid.

1. State how the magnetic field pattern indicates regions where the magnetic field is stronger.
2. What happens to the magnetic field when the current in the circuit is reversed?

Answer 1

1. Relative closeness of field lines indicates the strength of magnetic field. Since field lines are crowded around the ends of the solenoid, hence these are the regions of strongest magnetism. 
2. The direction of the field will also be reversed.