13.3 Magnetic force
What is the relationship between magnetic force, the movement of magnetic objects and energy?
A magnet attracts magnetic materials. When a stronger magnet is used, the magnetic force of attraction is stronger. Let us see how two magnets attract the same key.
When Magnet A is placed opposite an iron key, the key moves towards the magnet. When Magnet B is placed opposite the same key, the key also moves towards the magnet. The key is attracted to both magnets The key is attracted to both magnets but the key moves faster towards Magnet B than Magnet A. This shows that Magnet B is a stronger magnet and has a stronger magnetic force of attraction.
Magnetic force and energy
When the unlike poles of two magnets face each other, the magnets exert a force of attraction on each other. It is difficult to pull the two magnets apart. Thus, energy is required to pull the unlike poles of two magnets apart. The stronger the magnets are, the greater the energy is required to pull them apart.
Flashback
- A force o attraction pulls the unlike poles of two magnets towards each other. This force also pulls magnetic materials to magnets.
- A force of repulsion pushes the like poles of two magnets apart.
(a) When the unlike poles of the two magnets attract each other, energy is required to pull the magnets apart.