Magnets can be attached or combined together for either increasing or reducing their strength, depending purely on their orientation towards each other. Combining the two equal magnets will not necessarily double their strength, but definitely it will come close.
Combining the N-to-S
If north side of the one magnet combined with south side of other, so the poles get oriented N-S-N-S, then strength will definitely be close to the double thatof the single magnet, on a condition, if they are of the same strength and the shape.
Less Than Double
As the magnets don’t take or occupy the same space so the strength will not be doubled. Although the strengths of the field are additive, field strength on top surface of combined magnet is the distance away from other magnet – namely, width of top magnet away—therefore the full effect of bottom magnet does not felt.
Combining the N-N
If two magnets are combined and the same poles are facing each other, then their strength of the magnet will be greatly reduced. Strength will not be fully canceled out, as the argument which is stated above that they does not occupy same space.
Anyone may expect that the combined magnets would cancel, such as the electric charges. But the magnetic fields are additive instead.
The magnetism can be viewed as loosely oriented as created by circles that electrons create in their orbits and if the random orientation of these orbits is occurred they will cancel the each other. But if in the same direction they all are oriented then the strength of the field is additive and their effect is cumulative.
But do magnets get stronger when combined?
Answer of this question is here! When you stack the two identical permanent magnets then you get roughly strength of the one twice the size. A magnet twice or double the size, then it has to spread its energy of magnet over twice the volume, hence the strength of the surface of magnet is significantly rarely increased. The smaller neodymium magnets which have the same rating typically roughly have the same strength of the surface as the larger ones. It is the holding power that increases, as they have the larger surface area.
If you stack or combine the two magnets such that the opposite poles are touching each other then they will behave like the single magnet of same overall height. But if we see technically then this is not true 100%. When you stack the two magnets, actually you have little less magnetic material, as some of the plating layers you have in the middle which you are not having with single magnet. Still this is great approximation- we see hard to measure difference with pull force gauge.
In the today’s world, many the stacked magnets are being used in many of the applications and it has great usage. Let’s see forward in the future what applications of stacked magnet are more to be discovereed.