Electro-magnetism — Question 6

Which of the following statements is not true ?

1. The strength of magnetic field due to a bar magnet can be changed.
2. A solenoid behaves like a bar magnet i.e. it attracts iron filings.
3. The magnetic field increases if a soft iron core is placed along the axis of solenoid.
4. The magnetic field lines inside the solenoid are nearly straight and parallel to the axis of solenoid.