What is the difference between electromagnetism and electromagnetic induction

Induction Electromagnetic Induction - is the production of current in a conductor as it moves through a magnetic field. A magnet produces lines of magnetic force, as seen in the graphic above. Iron filings align themselves along the invisible lines of flux. Due to Faraday's Law of Induction if you take a wire and move it back and forth in a magnetic field, you cut across the lines of flux.

The magnetic field pushes on electrons in the metal. Copper has 27 electrons, the last two in the orbit are easily pushed on to the next atom. This movement of electrons is electrical flow. See the video below showing how current is induced in a wire:. If you take a lot of wire such as in a coil and move it in the field, you create a more powerful "flow" of electrons. The strength of your generator or motor depends on:. See the video to see all of this demonstrated:.

About the magnets:. In most electrical devices magnets are usually not made of natural magnetite or a permanent magnet unless it is a small generator , but they are copper or aluminum wire coiled around an iron core.

Each coil must be energized with some power to make it into a magnet. This coil around iron is called a solenoid. Solenoids are used instead of natural magnetite because the solenoid is MUCH more powerful. There are also some lesser common types such as anti-ferromagnetic materials and ferrimagnetic materials.

Diamagnetism is shown in atoms with only paired electrons. The total spin of these atoms is zero. The magnetic properties arise only due to the orbital motion of electrons. When a diamagnetic material is placed in an external magnetic field, it will produce a very weak magnetic field antiparallel to the external field. Paramagnetic materials have atoms with unpaired electrons.

The electronic spin of these unpaired electrons acts as small magnet, which is very stronger than the magnets created by the electron orbital motion. When placed in an external magnetic field, these small magnets align with the field to produce a magnetic field, which is parallel to the external field. Ferromagnetic materials are also paramagnetic materials with zones of magnetic dipoles in one direction even prior to the external magnetic field is applied.

When the external field is applied, these magnetic zones will align themselves parallel to the field so that they would make the field stronger. Electromagnetic radiation contains of two components, one electrical and one magnetic.

These components create each other, as said above. The red magnetic field creates a blue electric field, which creates the next magnetic field, and so on. From the Electromagnetic radiation Wikipedia :. Electromagnetic radiation is a particular form of the more general electromagnetic field EM field , which is produced by moving charges.

Electromagnetic radiation is associated with EM fields that are far enough away from the moving charges that produced them that absorption of the EM radiation no longer affects the behaviour of these moving charges.

What we were trying to do in your earlier question was really just picking up the weak magnetic field , because that's what a secondary coil does. I guess you're now wondering: but does a transformer do electromagnetic radiation, or is it just a magnetic field? Let's have a look, with the Electromagnetic radiation Wikipedia :. Think about the transformer. A magnetic field is generated when the current changes. You can already see those functions aren't in phase. They aren't in a constant ratio to each other either.

So no, a transformer does not radiate electromagnetic radiation. The waves aren't in a constant ratio of strength to each other, neither are they in phase. The tests you did with a transformer in your earlier question , were just based on a magnetic field.

This difference between picking up a magnetic field and magnetic radiation is known as the difference between near and far field. There are two main reasons why your experiments weren't about radio. The first is that it just was the wrong frequency.

The second is that a coil with an AC current does not provide electromagnetic radiation. Here's a picture from wikipedia on near and far fields: -. At about the wavelength of the antenna or the frequency you are using to couple energy the near field becomes the far field.

The far field is regarded as "proper RF" and is able to propogate with it's radiation decreasing as the square of the distance. Now consider a transformer at 50Hz - what is the wavelength - 6, km - will near field magnetic coupling work at even a 1,m - no. It's not rf. I think you already largely get it from your last sentence. A changing magentic field is not the same as radio.

Real radio is propagating energy. You can think of the energy as tied up in a specific dance between the E electric field and the B magnetic field. The two together oscillating in the right way cause the energy to propagate at the speed of light thru free space. Visible light is one example of this. It is a tiny part of the larger spectrum that goes down to but not at DC and up past gamma rays and cosmic rays. Common AM radio is at around 1 MHz, which has meter wavelength.

Common FM about times higher frequency and therefore times shorter wavelength, so MHz and 3 meters. WiFi operates at about 2. There are microwaves of a few 10s of mm wavelength, the "terahertz" radiation used at airports to look under your clothes, infrared, visible light roughly nm , ultraviolet, xrays, gamma rays, and on.

All these are exactly the same thing except for the frequency of oscillation. Since they all travel at the same speed of light in free space, you can also characterize them by their wavelength. The E and B fields can each support non-propagating fields too.

Wrap some wire around a steel bolt or ferrite rod, turn on the current, and you have a magnetic field. Ferromagnetic materials, like steel, will be attracted to this electromagnet. However, note that the energy of this field isn't being sent anywhere. The field exists around the electromagnet, and falls off rapidly with distance.

You can even vary the field over time by driving the electromagnet with AC current, and then have another nearby electromagnet work in reverse to make a electric signal in its wires from the changing magnetic field. In fact, this is the basis for how transformers work. Yes, you can transfer signals and even significant power this way, but it is not radio.

For example, there is no way to arrange a bunch of electromagnets to cause a beam of B field disturbance to be radiated in a particular direcation. You can shape the field locally, and the field does in theory extend to inifinity at the speed of light, but its not the same as sending a radio wave or light beam, or radar beam, etc.