Magnetic field lines of a magnet

What do the magnetic lines of force of a magnet look like? And how do they change with respect to the surroundings?
Below are some examples of magnetic lines of force of a magnet.
  • Magnetic lines of force of a disc magnet in free space
  • Magnetic lines of force of a disc magnet when a thin steel plate is placed on one side
  • Magnetic lines of force of a disc magnet when a thin steel plate is placed on both sides
  • Magnetic lines of force when two disc magnets are placed together
  • Magnetic lines of force when two disc magnets attract each other at close range
  • Magnetic lines of force when two disc magnets repel each other at close range

1. Magnetic field lines of a disc magnet in free space

2. Magnetic field lines of a disc magnet when a thin steel plate is placed on one side

3. Magnetic field lines of a disc magnet when a thin steel plate is placed on both sides

4. Magnetic field lines when 2 disc magnets are joined together

5. Magnetic field lines when placing 2 disc magnets attracting each other at close distance

6. Magnetic field lines when placing 2 disc magnets repelling each other at close distance