Difference Between Magnetic Flux and Magnetic Flux Density

Magnetic Flux vs Magnetic Flux Density

Magnetic flux and magnetic flux density are two phenomena encountered in electromagnetic field theory. These phenomena are extremely important in fields such as physics, electronic engineering, telecommunication engineering, electrical engineering and particle physics. A good understanding in magnetic fields is essential for the operation of the above mentioned fields. In this article, we are going to discuss about what magnetic fields are, what magnetic flux and magnetic flux density are, their significance, calculations and important aspects of magnetic flux and magnetic flux density, their similarities and finally their differences.

Magnetic Flux

Magnets were discovered by Chinese and Greeks in the period of 800 B.C. to 600 B.C. In 1820, Hand Christian Oersted, a Danish physicist, discovered that a current carrying wire causes a compass needle to orient perpendicular to the wire. This is known as the induction magnetic field. A magnetic field is always caused by a moving charge (i.e. a time varying electric field). The permanent magnets are the result of electron spins of atoms combining together to create a net magnetic field. To understand the concept of magnetic flux one must first understand the concept of magnetic field lines. Magnetic field lines or magnetic lines of forces are a set of imaginary lines which are drawn from N (north) pole of the magnet to the S (south) pole of the magnet. In definition, these lines never cross each other, unless the magnetic field intensity is zero. It must be noted that magnetic lines of forces are a concept. they don’t exist in real life. It is a model, which is convenient to compare magnetic fields qualitatively. The magnetic flux over a surface is said to be proportional to the number of magnetic lines of forces perpendicular to the given surface. The Gauss’ law, Ampere law and Biot-Savart law are the three most important laws when calculating the magnetic flux over a surface. It can be proved using the Gauss’ law  that net magnetic flux over a closed surface is always zero. This is very important because this shows that magnetic poles always occur in pairs. Magnetic monopoles cannot be found.

Magnetic Flux Density

Magnetic flux density, as the name suggests is the density of the magnetic flux over a given surface. This is proportional to the number of magnetic force lines normal to the given surface going through a unit area of the surface. Since the magnetic flux over a given surface is equal to the surface integral of the magnetic field intensity it can be shown that the magnetic field intensity and magnetic flux density are the same parameter expressed in different forms.