When most of us think of magnets the ones that come to mind are the small ones that we see in toys or use on fridges. The fact is that for most people magnets are first and foremost an amusement item.
Magnetism is a neat novelty and commercial magnets generally are sold solely for their appeal. However, even if you've only played with small magnets you've probably noticed that their power and range varies a lot.
Some magnets can lift metal off the ground without even touching it, while others barely budge their target even if they are next to it. This happens because “magnet” is a very broad definition.
Magnets can be made of many unique materials, in various sizes, and with completely different charges. So at the end of the day how far can a magnet reach? What is the real limit for magnetism? And what are some of the strongest magnets in the market right now? Keep on reading and you'll find the answer to all of those questions.
How Far Do Magnets Reach?
So How Far Do Magnets Reach? the reach of a magnet is something that is closely tied to its volume and material. So generally speaking the larger a magnet is the larger its practical reach should be.
To understand the reach of a magnet we first need to understand what a magnetic field is. A magnetic field is usually described as the vector a magnet or another magnetic object expands into its surroundings. Or in simpler terms, you can think of a magnetic field as all those invisible pulls that make a magnet attract metals. This means that the reach of a magnet can be summed up as the range of its magnetic field.
A magnet's field can be hard to calculate without taking into account its size and mass, but usually, its effective range can be calculated as the cubed distance.
Let's say you have a really weak magnet, one that can only lift paperclips at 1 inch of distance. If you try to do the same at 2 inches its pull would be up to 8 times weaker and its range would ultimately be ineffective. So in general for most household magnets their practical range is roughly their length, and anything past this will cause their strength to drop considerably.
What is the Strongest Magnet Ever?
If you want to get technical the strongest magnet on our planet is the Earth itself. Some of the inner layers of our planet are permanently magnetized, and its core also produces a magnetic field of its own. The Earth's function as a magnet is the whole reason compasses work. Compasses can guide us towards the north because they are attracted to the natural magnetic field Earth produces so they always guide us roughly towards the north pole.
The Earth's magnetic field extends out to roughly 65,000 kilometers above the surface of the planet, far beyond Earth's actual atmosphere which is measured at 10,000 kilometers. That said the internal heat of the planet and the voluble nature of magnetic fields means that the Earth's range can vary based on where you measure it. And we should also clear up that the earth's magnetic field doesn't play a role in gravity, they are two completely different forces.
The strongest man-made magnet on the other hand resides in Tallahassee, Florida. The MagLab DC Magnet can maintain a continuous magnetic field of 45.5 Teslas, a feat that granted it a World Record. For reference an average fridge magnet measures at 0.0001 Teslas, so the DC Magnet is on a completely different league.
The most impressive fact is that its creators at the Magnetic Field Laboratory are pushing for even stronger magnets moving on forwards. Their current goal is to reach 50 Teslas so the world's strongest magnet could very well become outdated in just a few years.
How Far Can a Magnet Repel Another Magnet?
If it comes down to household magnets don't expect to get much more distance than a few feet. When it comes to permanent magnets their forces are generally on the range of human effort. Or in short, they are designed so you can easily pull them off apart with your own hands. So your average magnet will simply provide a slight push to its peers. You can increase the range a bit if you repel a small magnet with a larger one, but it still won't amount to much.
Electromagnets on an industrial range however are a completely different matter. Electromagnets are so reliable at pushing other objects that we made a weapon out of this principle.
A “Railgun” is a weapon that uses electromagnetism to accelerate a projectile to speeds far above what traditional ballistics can hope to match. So while traditional magnets don't have much push to them, an electromagnet can be as destructive as its power capacity allows.
How Far Can a Magnet Attract?
Theoretically, magnets should be able to attract each other regardless of the distance, but this doesn't work in practice. Magnetic fields technically don't have a limit to their range and as such magnets in theory can attract each other regardless of distance.
Of course, this doesn't happen in our day-to-day life, otherwise, we would have magnets crashing into each other all over the world. While a magnetic field might have a wide range we also saw that the force of a magnetic field falls off very rapidly, and it's not like magnetism is the only force affecting magnets at all times.
If you push two magnets far enough from each other that they stop attracting each other this doesn't mean their magnetic properties completely drop off at that distance. it simply means that at this range their magnetic fields are way weaker than gravity, friction, and all the other factors keeping the magnets in place.
Gravity in general works very similarly to magnetism, but it's generally stronger than it. So magnets will have a hard time overcoming gravity unless they are close to each other.
Do Magnets Have Infinite Range?
Theoretically yes, magnets on ideal circumstances electromagnetic forces are considered to have an infinite range. But this doesn't necessarily mean all magnets in the world are attracting each other right now.
In physics, there are four fundamental forces that help explain the way our universe works, and magnetism falls under electromagnetic force. The thing with electromagnetic forces is that they ultimately have an infinite range. Unlike other forces electromagnetism doesn't rely on a basic particle to transmit its force, An easy way to look at this is as if magnetism is a train that doesn't need any rails to advance, meaning magnetic pulls theoretically don't stop.
However, when it comes to theoretical physics it's important to remember that they don't translate perfectly to our real world. Electromagnetism as its name implies is tied to electrical charges, and the universe is full of electrical charges all over it.
So in the same way two magnets can repel each other, a magnetic field can be canceled by another or stray charges. Therefore, in practice, a magnetic field is bound to find a charge that will cancel it in due time, and the real range of magnets is limited by these circumstances.
On the other hand, if you could place two magnets in a perfect environment without any sort of interference for their magnetic field they should attract each other regardless of distance. It just would be a very slow process since the power of magnetic fields falls off very quickly.
Despite their apparent simplicity magnets are incredible little items, and as we just saw trying to determine just how far can a magnet reach requires a deep understanding of physics.
Due to the way electromagnetism works magnetic fields can technically extend to an infinite range. However, there are three main factors keeping magnets from having limitless range.
- First and foremost the power of a magnetic field drops off at a really fast rate, and the cubed distance formula shows us it only gets exponentially weaker as the distance grows.
- The second issue that magnets face is that electromagnetism can be canceled, other magnetic fields or stray charges can cancel out their field, and as such their real range is very limited in practice.
- And last but not least gravity is also an infinite range force and it's generally stronger than electromagnetism, so magnets just aren't strong enough to get past gravity most of the time.
In short, electromagnetism might have infinite range and reach, but magnets don't. And for household magnets, their reach can generally be treated as their overall length. If you want to get a magnet with a longer reach than that you will need to delve into the world of electromagnets.
- Q & A: magnet at a distance | Department of Physics | University of Illinois at Urbana-Champaign
- What are magnetic fields? (article) | Khan Academy
- Does The Earth's Magnetic Field Go Past The ISS? (forbes.com)
- Is the Earth a magnet? (usgs.gov)
- Magnet Sets World Record at 45.5 Teslas – IEEE Spectrum
- Fundamental Forces (gsu.edu)
- Why is gravity the strongest force? | Science Questions with Surprising Answers (wtamu.edu)
- Railgun – Wikipedia