How can you increase the strength of a permanent magnet?

Hint: Firstly, we will understand what are temporary and permanent magnets. We will understand the reasons for the demagnetization of the permanent magnets. Then, we will discuss the method of strengthening the permanent magnetic material using some other strong permanent magnetic material.

Complete step by step solution:
Temporary magnets are the substances that get magnetised for a short period of time. Temporary magnets act as permanent magnets only when in a strong magnetic field. Temporary magnets lose their magnetism when the magnetic field disappears. Examples of temporary magnets are paperclips, iron nails, etc.

Permanent magnets are the magnets that retain their magnetic properties for a longer duration of time. Examples are nickel and cobalt. No doubt, it is possible for a permanent magnet to lose its strength. Over a longer period of time, magnetic properties are most likely to decay due to these reasons:
- Random temperature fluctuations
- Stray magnetic fields
- Excessive or heavy mechanical movements

Now, to increase the strength of a weakened permanent magnet, one can find a stronger magnet and stroke it with the weaker one, making sure that only the opposite poles are in contact with one another and that the strokes are unidirectional or in a single direction.
The electrons of the weak permanent magnet will realign themselves again due to the linear strokes, when the process is continued again and again. This activity will increase the strength of the permanent magnet.

Note: We can also use the magnetic influence of excitation coils to strengthen the magnetic field around the permanent magnet. Electric current also has its magnetic effects. Current forms a magnetic field around the region it flows. Permanent magnet can be strengthened by keeping in influence of electric current carrying an excitation coil.