Understanding magnetic field, magnetic flux, and magnetic flux density

 Analogies are often effective in explaining matters relating to physics most especially when two or more terms sounds quite similar and complicated. In our previous post, we were able to explain speed, velocity, and acceleration using analogies and in today's post, we have yet another group of physics philosophy which sounds quite similar and complicated to understand. So we'll try and break it down by applying it rules to a more common objects. Let start by their definitions.

Magnetic field

A magnetic field is a region around a magnet or a current-carrying conductor, where a magnetic force is experienced or where a magnetic force exist. The direction of this magnetic field is represented by magnetic field lines.

Magnetic flux

The magnetic flux  is therefore proportional to the number of magnetic field lines passing through a magnetic field. For simplicity sake, just view the magnetic field lines as just the individual lines, then view the magnetic flux as the whole lines put together. The magnetic flux determines the strength of a magnetic field, i.e the more the magnetic flux set up, the stronger the magnetic field. Therefore, the magnetic flux is the net number or quantity of the magnetic field lines set up or produced in a magnetic field.

Magnetic flux density

This is defined as the magnet flux per unit area in a given magnetic field. While the magnetic flux determines the total strength of a magnetic field, the magnetic flux density determines the strength of a magnetic field just IN A GIVEN AREA. 

Now let move to the analogies.

Magnetic field: Let use a standing fan as an example. When you switch on the fan, it will blow the air around itself and you will feel the air. When you move closer to the fan you will feel the air pressure more intense. When you move farther away from the fan you will feel the air pressure lesser and as you continue to move away, the air pressure diminishes. Now let take the region that you experienced the air as fan field. If we are to define the fan field, we would say that the fan field is a region that a fan force(which is air) is experienced. Comparing it to the magnetic field, the magnetic field is just a region that a magnetic forced is experienced. But we humans cannot experienced a magnetic force but metals do.

Magnetic field lines: The standing fan is pushing the air towards a specific direction. But can we see it. No. But we can thus feel it. In fact if we were to draw lines representing the direction of the air, all we have to do is we will just try to visualize where we're recieving the breezes from and then draw an imaginary line showing the direction of the air. That is what magnetic field lines is all about. Magnetic flied lines(or magnetic lines of force) is just an imaginery line that shows the direction in which a magnetic force is comming from.

Magnetic flux:  A magnetic flux is represented to be the whole magnetic lines of force put together. Let consider a moment when the fan blades rotate at high speed, we will notice that even if we move farther away from the fan and in a slightly different direction, we will still feel the air intensely and the number of our imaginary lines will appear to be much because we will be receiving the air from all directions. So likewise, when the magnetic field is stronger, it will generate more magnetic field lines which will increase the magnetic flux. 

Magnetic flux density: To understand magnetic field density, let take a different approach. Let use the aspect of population density. The population density of a country is just a net number of people living in a particular country(maybe china). So the magnetic flux density is the amount of magnetic flux present in a given area. NOTE; "a given area" in a magnetic field not the whole magnetic field area. Just as the population density of a country can be greater or less than the one in another country. Likewise, the magnetic flux density in a given area can be greater than the one in another area. Consider when you stand by the side of the fan,, and when you stand in front of and when you stand at the back of the fan. You won't receive the same intensity of air, because the air density  varies from region to region.