Magnets and Magnetic Strength
MAGNETS - BASIC TECHNICAL INFORMATION
Although Magnetic Therapy is often quite simple in its application, there is a certain amount of technical jargon associated with magnets. To help with some of the magnetic jargon that is often used with these products we have summarised the main ideas below.
· WHAT ARE MAGNETS?
· WHAT ARE MAGNETIC POLES?
· HOW IS A NORTH POLE DEFINED?
· WHAT DOES UNI-POLAR AND BI-POLAR MEAN?
· HOW STRONG IS A MAGNET?
· SURFACE GAUSS READING vs MANUFACTURERS RATING
· HOW IS GAUSS STRENGTH MEASURED?
· IS THE HIGHEST GAUSS MAGNET THE BEST?
· IS HAVING MORE MAGNETS BETTER?
· ARE THERE DIFFERENT TYPES OF MAGNET?
· HOW CAN I IDENTIFY THE POLES OF A MAGNET?
· HOW LONG WILL A MAGNET LAST?
What are Magnets?
A magnet is an object that has a magnetic field. The word magnet comes from the Greek "magnítis líthos", which means "magnesian stone". Magnesia is an area in Greece where deposits of magnetite have been discovered since antiquity.
In the modern sense, a magnet is any material that has a magnetic field. It can be in the form of a permanent (or static) magnet or an electromagnet. Permanent magnets do not rely upon outside influences to generate their field. Electromagnets rely upon electric current to generate a magnetic field--when the current increases, so does the field. The magnets normally used in Magnet Therapy are permanent.
What are Magnetic Poles?
Poles apart! All magnets have two poles, a North pole and a South pole. Opposite poles attract each other (North attracts South), while like poles repel (North repels North, and South repels South).
The Earths Field: The Earth has a magnetic field with a North pole and a South pole. The strength of the Earths magnetic field is approximately 0.5 gauss. All life; human, animal and plant is born and lives out its life under the influence of the Earths Magnetic field, magnetism is a natural part of life like water and air.
How is North Pole Defined?
There is much confusion around this issue mainly because there are different conventions or starting points about how to define a north pole. There is an engineering and scientific convention; but there is also a medical or magnetic therapy understanding.
Bio North: The magnetic therapy starting point says that the Earths geographical North Pole is a magnetic north pole, therefore whatever points to the north pole i.e. the end of a compass needle, is a south pole (as opposites attract). This is the common sense approach, i.e. the Earths North Pole is a north pole. A north pole from this point of view is often called Bio North or Negative North. The end of the compass needle with the N or arrow will point to the Bio North pole.
Science: Defines a north pole as the end of the magnet which points to the geographical North Pole, in other words it is actually saying that the Earths geographical North Pole is a magnetic south pole.
What does Uni-polar and Bi-polar mean?
Uni-polar: means using just one pole of a magnet, this usually means that on one side of the magnet you mainly get one pole (e.g. north), while the other side of the magnet you get the opposite pole (e.g. south).
Bi-polar: means using two poles, north and south, at the same time, on one side of the magnet. But it must be noted that even with uni-polar magnets you still get a small percentage of the opposite pole on one side of the magnet as the magnetic field start to turn near the edge of the magnet into its opposite pole.
How Strong is a Magnet?
Magnetic strength is not an easy or straight forward concept as it depends on several factors. In a magnetic device (eg a magnetic bracelet), the overall magnetic strength depends on three main factors: 1) the GAUSS rating of each magnetic, 2) the actual PHYSICAL SIZE of the magnets, and 3) the NUMBER of magnets in that device.
Gauss Rating: Magnets are given a Gauss rating, this is a unit of measurement that relates to the strength of a magnet and is connected with the density of lines of magnetic force coming from a magnet. You could say that this is like the pulling power of a magnet. In engineering and the physical sciences another unit of measurement is used, this is the Tesla, (10,000 gauss = 1 Tesla). In magnet therapy people tend to use the gauss rating.
Magnet Size: It must be noted that the pulling power or strength of a magnet is also related to the actual physical size of a magnet. Larger magnets have more mass than smaller magnets and so can store a greater amount of magnetic energy. So you could have a magnet with a very high gauss rating which will in fact have less overall strength that a much bigger magnet with a lower gauss rating. The size of the magnet contributes to the depth of penetration of the magnetic field into the body. Gauss rating alone is not enough to indicate the strength of a magnet.
Surface Gauss Reading vs Manufacturers Rating (or Grade)
Quite often gauss magnetic strength is misquoted or exaggerated. One common misunderstanding is the difference between what is called the Manufactures Rating (or grade) and the actual Surface Gauss Rating of a magnet, as one figure is much higher than the other, and represents two different ways of measuring the strength.
Manufacturers Rating: Technically this is called the Magnetic Remanence (Br) of the magnetic material and is a property of the magnet when measured in the manufactures original magnetising equipment, in what's called a closed circuit. It indicates the magnetic field strength remaining inside the magnet (or at its core) and represents a grade of magnetic material. This measurement is much higher than the surface gauss reading.
Surface Rating: The gauss rating is measured on the surface of the magnet and represents the magnetic flux density generated outside the magnet body. Strictly speaking this is the rating which is most useful to a Magnet Therapist as it is more indicative of the magnetic energy that will penetrate through human skin and tissue.
How is Gauss Strength Measured
Believe it or not magnetic Gauss strength is measured using a Gauss Meter (to measure surface gauss strength). These are quite complex instruments which cost several hundred pounds.
Is the Highest Gauss Magnet the Best?
As mentioned above, magnetic strength is not only related to the gauss rating of a magnet but also to the magnets physical size. The size of the magnet contributes to the depth of penetration of the magnetic field into the body. Gauss rating alone is not enough to indicate the strength of a magnet.
Is Having More Magnets Better?
Generally yes, having more magnets in a given product can improve the therapeutic outcome. But it will depend on what area of the body one is treating, the location and strength and size of the magnets. As an example a 6 magnet bangle is better than a 2 magnet bangle, simply because with 6 magnets the magnetic fields generated have a better chance of influencing the blood flow at the wrist arteries.
Some companies add up the gauss rating of each magnet in a given product and quote this as an overall gauss rating for the product. This is incorrect both technically and medically; magnetic gauss rating cannot be simply added in this way. The motivation of these companies is to try and present the product with what sounds like a huge gauss rating in order to achieve sales.
Are there Different Types of Magnet?
There are several different types of material that magnets are made from. The main two types used in magnetic therapy are Ferrite sometimes called ceramic magnets and neodymium magnets.
Ferrite or ceramic magnets: are made of a mixture of iron and barium. They can be made into large shapes and hold their magnetic strength for many years.
Neodymium magnets: Is a more recent discovery, and are made of iron, boron and the rare earth neodymium. These magnets are very strong in comparison to their mass and also hold their strength for many years. Neodymium magnets have 10 x the power of Ferrite magnets. Neodymiums cannot be made very large.
How can I Identify the Poles of a Magnet?
These notes correspond to the convention used in Magnet Therapy where North is called Bio North or Negative North, as described above.
Polarity can be identified using a compass, when the Geographical North end of a compass needle (often marked with an N, or with an arrow) points to a face or side of a magnet, that side of the magnet is Bio North.
The polarity can also be determined using another magnetic of known polarity, using the principle of attraction and repulsion.
How Long will a Magnet Last?
The effect of time on modern permanent magnets is minimal. Over a period of 10 to 15 years in normal use, a magnet will loose only a tiny fraction of its magnetisation. Magnets will remain magnetised for several decades.
Disclaimer: We make no specific medical claims. It is always best to seek professional medical advice on an individual basis for your particular circumstances.