Magnets, whether they be natural or man-made, are incredibly useful in a vast number of situations. They can range anywhere from small magnets used to hold coupons on the fridge, all the way up to massive, incredibly powerful ones used for industrial applications.
Because magnets are so useful in such a large number of situations, they are also used all over the globe in several different environments. Many of these applications take place in or around water, and they even find uses far beneath the surface of the ocean.
However, water is known to have some strange effects on the world around it and doesn't always operate by the same rules that air does. This then begs the question: do magnets still work underwater? Furthermore, does being submerged in water make magnets stronger or weaker?
The good news is that just dipping a magnet in water isn't going to irreparably neutralize its magnetic properties. In all reality, water has very minimal effects on magnetism, and really isn't going to change a magnet's performance in any way that is significant or observable.
Only under very specific situations will water have any real effects on a magnet's properties, but they are fairly uncommon and are usually only purposely achieved. Realistically, the only water-related issue to worry about when concerned with magnets is that of rust and corrosion.
How Do Magnets Work?
Magnetic fields, which result in objects either attracting or repelling each other, are created when electricity is passed through an object that is capable of magnetism. However, there are some natural magnets that exist without the help of electricity.
Both electricity and magnetism are created by the interactions that charged particles have with each other, also known as electromagnetism. Electricity is the free movement of charged particles, while magnetism is the attractive and repellant forces that form between two charged particles in movement.
Magnetic fields and domains, or the area of an object that is magnetized, are created when the charged electrons found in an object's atoms are arranged to move in the same direction. The bigger and more magnetic domains are aligned with each other, the stronger the magnetic pull will be. This alignment will create two poles: north and south. Opposite poles will attract, while like poles will repel each other.
The strength at which two magnets attract each other largely depends on how close they are to each other, as well as the angle they are at. The closer the magnets are to each other, the stronger their attraction or repulsion will be. Furthermore, the angle at which the two magnets are positioned in relation to each other will change the strength of their interaction.
However, if there are objects in the surrounding environment that are exerting an additional force on the magnets, it may alter the way that they interact. For example, if the environment is filled with other magnets or magnetic objects, it may be difficult to determine what exactly is a result of the initial magnetic attraction or repulsion that you were attempting to observe.
Do Magnets Work in Water? What Happens When They are Placed in Water?
The simple answer is: yes, magnets still work even in water. Simply placing a magnet in water does not change its magnetic properties in any way. Much like light and electricity, magnetism is not hindered by a watery environment.
Furthermore, because water has practically no magnetic force in and of itself, it does virtually nothing to alter the way that magnets and magnetic objects interact with each other. So long as the magnets in question aren't surrounded by other magnetic fields that may alter their interaction, simply adding water will do practically nothing to either strengthen or weaken their attracting or repulsion.
Water is technically diamagnetic, meaning that it is actually repelled by magnetic fields. However, because this repulsion is so weak, it is nearly unobservable without specialty equipment. While there are superconductors that repel any magnetic field, and can even be observed floating above magnetic domains if strong enough, the interaction that water has with magnetic fields is practically negligible.
At the same time, some objects are known to be ferromagnetic or have a high susceptibility to interacting with magnetic fields. These are objects that we commonly think of as being magnetic, such as iron and nickel. Because objects such as these react so strongly to magnetic fields, they have a tendency to “short-circuit” or disrupt magnetic fields. Water, however, is very far removed from this category.
However, water does have a very interesting effect on the effectiveness of magnets due to a phenomenon known as effective weight. Effective weight essentially means that objects “weigh” less when placed in water, and are therefore easier to move. While the object's actual weight has not changed, it is much easier for forces exerted on the object to move it. Because of this, while a magnet's strength doesn't change when placed in water, it will be able to move magnetic objects much more effectively; it may be able to attract heavier objects or even move a larger number of individual objects.
Do Magnets Lose Their Magnetism in Water?
Water by itself does not change the magnetism of a given object. However, if the magnet begins to rust and corrode, it will begin to see a decrease in the strength of its magnetic properties. Corrosion occurs when an object breaks down upon interacting with its environment, and rust is a type of corrosion.
As a magnet corrodes away, it will naturally become weaker. This is especially true for neodymium magnets, which have a very high level of iron content. Because of this, it is far more susceptible to rust and therefore deteriorates in water much faster than other magnets with lower iron contents.
Examples of Magnets Used in Water
There are plenty of specialty magnets that are designed for use in a liquid environment. These magnets are able to withstand the potential physical decay that may come from prolonged submersion, which will be further discussed later in this article. Such magnets include, but are not limited to:
Magnetic Laboratory Stirrers
Magnetic laboratory stirrers are plates that a container with a mixture and a small magnetic bar are placed on top of. The magnetic field then rotates, pulling the magnetic bar along and rapidly mixing the contents of the container. These tools are especially useful in mixing sealed containers and obtaining evenly distributed and consistent mixtures.
Magnet Mines
First implemented by the Germans in World War II, magnet mines were underwater explosives that were able to detect magnetic disturbances created by large metal objects, such as ships and submarines. When a sizable interference was detected, it would trip an internal mechanism, causing a violent explosion.
Magnetic Torpedo Triggers
Magnetic torpedo triggers, also known as magnetic pistols, are similar to magnet mines, in that they are able to detect magnetic disturbances. However, instead of being a stationary explosive, they are attached to a torpedo which is then purposely fired under a ship instead of into it. When detonated from underneath a ship, it is liable to cause far more irreparable damage to the vessel and is therefore far more devastating.
Aquarium Magnets
Aquarium magnets are designed to be used in aquariums both large and small and usually stay submerged for a large majority of their lifespan. They can be used for a variety of applications, such as holding environmental pieces in place and dragging cleaning pads across the inside of the aquarium using an external handle.
Does Water Temperature Make a Difference?
The temperature of the water in question does not affect magnetism in any significant way. Warm water may result in the slight weakening of a magnet, as it may slightly rearrange the magnetic domains, resulting in them no longer aligned in the same direction.
However, this change is practically negligible. When placed in extremely hot conditions, a magnet will completely lose all magnetic properties. However, this temperature is far above the boiling point of water. Cold water, on the other hand, has even less of an effect, only slightly increasing magnetism in extremely cold conditions.
At the same time, objects will be able to move faster towards or away from a magnet when placed in hot water. This is due to the fact that friction is decreased in hot water. When the temperature is increased, the water becomes “thinner” as the bond between its atoms is weakened, and the water becomes less viscous.
This is why water changes states of matter once it starts to boil; as the bonds break down further, allowing the molecules to separate even further. Thus, while the magnet is not technically any stronger, it will appear to have a stronger effect on objects the hotter the water is.
What Would Happen if you Froze a Magnet in Water?
Freezing anything will cause the random movements of its magnets to decrease. As this article has previously discussed, a magnet needs its electrons to align in one direction and stay that way in order to have a strong effect. Because of this, the further that the temperature of the magnet is decreased, the stronger it will become.
At the same time, it is important to consider that in freezing a magnet in water, it will become locked in position, and will only be able to get so close to other magnetic objects. Because of this increased distance, it may slightly alter the strength of its attractive and repulsive properties.
However, there comes a certain point where further decreasing the temperature will diminish an object's magnetic properties. At such extreme temperatures, certain magnets will actually lose magnetism as molecules begin to fall out of their “good” alignment.
Does Getting a Magnet Wet Ruin it?
With certain magnets, it is imperative to keep them dry to prevent rusting. For example, iron magnets must be dried off to prevent deterioration which may affect the magnet's overall performance and appearance. Other than rust, water itself will not damage a magnet in any way.
Any changes that water may have on a magnet's performance, such as that imposed by extreme temperatures, will be immediately reversed upon removing the magnet from the water, cleaning it, and allowing it to return to room temperature.
Are Ceramic Magnets Waterproof?
Ceramic magnets are relatively cheap permanent magnets that are mass-produced for a variety of purposes. These magnets are extremely difficult to rust due to the fact that they are made of Ferrosoferic Oxide, a compound that is already an iron oxide.
Rust occurs when a metal becomes oxidized, or reacts with oxygen. Normal iron has not yet been oxidized and is therefore far more reactive when exposed to water and oxygen. Ceramic magnets, on the other hand, are far more resistant to a second round of oxidation and are therefore nearly impervious to rust.
Do Neodymium Magnets Rust in Water?
As discussed earlier, neodymium magnets are particularly sensitive to rusting due to their high level of iron content. Never put a neodymium magnet in water for an extended period of time without some form of protective coating. Furthermore, once the magnet is removed from the water, be sure to dry it off right away to prevent rust from forming.
How to Waterproof a Magnet to Prevent Rust
Pre-waterproofed magnets are very common and not particularly difficult to come across. However, there are a variety of ways to DIY a waterproof coating to protect magnets from rusting when in contact with water.
The best waterproofing method is to cover the magnet in a thin coat of waterproof material that will keep moisture out without affecting its magnetic properties.
Such coatings include:
- Waterproof epoxy putty
- Two-part epoxy
- Multipurpose rubber dip
- Enamel paint
- Hot-melt adhesive
Waterproofing a magnet is relatively cheap and easy; the biggest concern is to ensure a tight seal in order to prevent any water from coming in contact with the magnet itself.
What Happens When a Magnet is Placed in Liquids Like Acids, Bases, and Salt Water?
While we have discussed pure water up until this point, the game may be slightly changed with the introduction of different types of liquids. The first issue to consider is that of paramagnetism. Paramagnetism is the opposite of diamagnetism; instead of being repelled by magnetic fields, such substances are attracted to them.
This comes into play when one considers the fact that the above examples are solutions of different things dissolved into water. When these molecules are weakly paramagnetic, they may then react with magnets in ways that the water itself does not.
When these molecules are paramagnetic, the introduction of a magnetic field may then in turn give them their own slight magnetization. While this may theoretically change the magnet's performance, the effects are practically negligible.
However, take a highly paramagnetic liquid such as liquid oxygen into consideration. When introduced to a magnetic field, the attraction that it has to said object is strong enough that it can be observed with the naked eye. This is due to the fact that every molecule in this liquid is highly paramagnetic, and therefore every single molecule is being affected by the magnet.
Less paramagnetic solutions, on the other hand, only have a certain number of their molecules reacting to the magnet, and their reactions are being suppressed by the overwhelming majority of diamagnetic molecules. While such an attraction is still technically occurring, it is far more difficult to observe.
In saltwater, water's nearly nonexistent diamagnetic properties are reduced even further. Because of this, it no longer repels a magnetic field.
In regular water, a strong enough magnet would be able to interact with a diamagnetic object, such as a few drops of oil, and raise it to the water's surface. However, with the reduction of the saltwater's magnetic field, the magnet would no longer be able to cause the oil to float.
While the magnet's properties have not technically changed, it has reduced its ability to interact with certain objects. While its attractive properties will not change, its ability to repel diamagnetic objects is practically neutralized.
Furthermore, saltwater also accelerates the rusting process, causing magnets to corrode and weaken at a much higher rate. Saltwater is an electrolyte solution, meaning that it is much easier for ions to move freely about. Rust occurs when electrolytes are released from a molecule, and with the increased ease of movement that occurs in saltwater, it is much easier for metal to lose its electrons and rust far faster.
Conclusion
Magnets are not affected by water in any particularly significant way. Except under very specific circumstances, such as extreme temperatures or when part of an overall paramagnetic solution, don't expect to see any observable changes in a magnet's performance.
The biggest issue to consider when placing a magnet in or around water is preventing any rust that may occur. If you need a magnetic for an underwater application, consider purchasing a ceramic magnet, or one that is designed specifically for use in wet or humid environments. Otherwise, be sure to waterproof the magnet so as to prevent deterioration over time.
Sources used:
- https://www.ipesmag.com/can-magnets-work-underwater/
- https://van.physics.illinois.edu/qa/listing.php?id=368&t=magnets-under-water
- https://www.quora.com/Do-magnets-work-in-water
- https://sciencing.com/salt-water-rust-metals-5150093.html
- https://www.apexmagnets.com/news-how-tos/what-will-happen-to-a-magnet-in-water/
