The magnetic strength of a magnet is determined by the alignment of the electron spin direction in a metallic lattice. In a solid metal, the metal atoms are bonded to one another in a regular lattice framework.
When heated up to a near melting point, the atoms can be aligned in a strong electric field to have their electrons spin in the same direction causing the metal to become magnetic.
- Over time the field strength of a magnetized metal will decrease
- The alignment in a uniform direction of electron spin is decayed due to external influences.
- The second law of thermodynamics dictates that the ordered state will tend to disorder over time, weakening magnetism.
Magnets and magnetic fields are fascinating subjects of study. The center of the earth is thought to consist of a solid Iron sphere responsible for the earth’s magnetic field.
Were it not for the magnetic field around the earth, the electromagnetic rays from the sun would strip the earth of the atmosphere and leave the planet lifeless. Let’s look at the fascinating field of magnetism more closely.
How Magnetism Protects The Earth For Now
The earth’s magnetic field or magnetosphere creates an invisible deflection shield that prevents most of the solar radiation from stripping the atmosphere from around the earth. The magnetic deflection prevents high-energy cosmic radiation from causing our cells to mutate and become cancerous.
Our nearest planet Mars once had a magnetosphere much more potent than today. The movement of molten metal between the metallic core and the outer layer of the core created a strong magnetic field around the planet, called the magnetosphere.
Over millions of years, the core of Mars cooled down, and the movement of the molten iron became slower.
The result was that the magnetosphere reduced and could no longer protect the atmosphere and surface of Mars from the high-energy solar rays and cosmic radiation.
- About 4.3 billion years ago, Mars looked a lot like earth does today, with a thick atmosphere and water on the planet’s surface.
The loss of magnetic strength caused the magnetosphere to diminish until it could no longer prevent the high energy radiation, also called the solar wind, from stripping away the atoms and molecules in the atmosphere of Mars until the surface became dry and lifeless.
Some traces of water were recently found on Mars, frozen underground and protected by the layers of rock above. The same fate awaits our planet some time billions of years in the future. We have experienced the effect that solar storms on the sun can have on earth.
Coronal mass ejections are massive storms raging on the sun and ejecting high-energy radiation out into space. These storms can be so powerful that they cause damage to communication satellites orbiting outside of the earth’s atmosphere.
These coronal mass ejections from the sun can cause power outages on earth as the radiation damages electrical equipment.
How Are Magnets Made?
Electromagnets are made by winding an electrical wire around an iron bar. The ends of the wire conductor are attached to the positive and negative ends of a battery. An electrical current will pass through the wire and induce a magnetic field at a ninety-degree angle to the direction of electron flow.
The electrons inside the iron bar will align themselves with the induced magnetic field, making one end of the iron bar the north pole and the other side the south pole. The iron bar will only maintain this magnetic field while the electrons’ current flows through the wire.
The iron must be heated to near melting temperature and then subjected to the electromagnetic field to create permanent magnets. The metal must be cooled down to room temperature while maintaining the electromagnetic field.
This will cause the alignment of the iron atoms in the metallic lattice to be fixed in a direction causing the iron bar to be a permanent magnet.
The magnetized iron bar will maintain the strength of its magnetic field for a very long time, and only the impact of heat and physical shock to the metal will disrupt and destroy the alignment of the iron atoms.
This is a prolonged process as it takes place inside a solid metal where the movement of atoms is restricted.
Why Do Magnetic Field Strength Deteriorate?
The second law of thermodynamics states that all systems of the order will naturally decay towards disorder.
When applied to a simple bar magnet, this law accurately predicts that the magnetism of the magnetic bar will reduce over time until it is completely gone.
The magnetized state is induced on the electrons that orbit the iron atoms in the metal bar by applying a strong magnetic force field to the metals bar.
The force field will cause the electrons to align in their spin direction, making the metal bar magnetic. As the spin direction randomizes again over time, the bar will lose its magnetism.
Who Discovered The Principle Of Magnetic Induction?
Michael Faraday made the discovery in 1830 that a changing magnetic field induces an electric current in a conductor. An electric motor consists of multiple coils of copper wire that are rotated by the magnets placed around it, resulting in a rotational force.
Magnetic induction has led to the invention of electric generators, transformers, and electric motors that are the foundation of modern society.
The turbines of a generator can be rotated by the force of pressurized water or steam, causing the copper loops to turn between massive magnets and resulting in the flow of electrons.
How Large Can Magnets Be?
Magnets exist in all sizes, from sub-atomic particles to industrial-size magnets to planets and stars that have means they each have two poles.
From the largest stars in the universe to sub-atomic particles exhibit magnetic fields and exist due to their magnetic nature.
A magnetic field is often depicted as lines of magnetic flux. In the case of a bar magnet, the flux lines exit from the north pole and curve around to reenter at the south pole.
In this model, the number of flux lines passing through a given surface in space represents the field’s flux density or strength.