Ultraviolet UV Safety. Non-ionizing radiation includes radio, microwave, infrared, and visible light. Magnets, UV and Radio Frequency. Expand All Magnet Safety. Transient Electromagnetic Fields are produced by the switching of inductive loads such as circuit breakers or motors. Lightning will also cause this type of disturbance. A transient signal in a cable produces a radiated emission with a spectral content dependent on the amplitude, rise time and pulse width of the transient.
The reception of broadband fields at the lower frequencies is mainly via cables, which are electrically long with respect to the wavelength. A cable longer than one quarter of a wavelength will be an efficient receptor. Broadband radiation from transient sources is rarely found to have significant energy at frequencies exceeding MHz.
Conducted interference may originate from the coupling of ambient radiated interference or may be capacitively, inductively or galvanically induced in the cable by an emitting source. While WIFI, cellular networks, or broadcasting TV sound like very sophisticated technologies, they all rely on a straightforward trick, which has been with us since the creation of the most elementary electronic telecommunication systems, which was the Morse telegraph and its predecessors.
This is the ability of electricity to produce magnetism and vice-versa. In fact, electricity and magnetism are the same things! Electric power is one of the four fundamental forces of nature. The other three are gravity and two more invisible forces that can only be observed within some sub-atomic particles.
Conventionally the last two are called the weak and the strong atomic forces. NB, gravity is not the same as magnetism. If midichlorians are responsible for any, all, or none of these forces, I honestly do not know.
What I know, however, is what electromagnetism is: the fabric of nature. Electricity exists in every single atom. It is, in fact, what makes the electrons and protons you learned about in school special. You might imagine these two particles as little billiard balls spinning inside and around the nucleus of the atom but, in fact, both are clouds of electric energy.
Electrons are charged negatively, protons positively. When electromagnetic energy manifests itself, it does several things.
First, it can release its energy as spectacular explosions. This is what happens when you short a light or when lightning hits a tree. More subtly, you might observe that in electrically charged situations such as a storm , hairs start standing on an end. This is because the strands of hair are electricity laden, which makes them magnetic, which makes them reject each other. All electrically charged objects can attract objects charged with the same energy, since, remember, electricity is magnetism.
More important, objects that are magnetic can be used to produce electricity. All electric power plants do is to spin magnets inside wire coils. That is where electricity is coming from. You can replicate this by moving a magnet through a coil of copper wire.
The truly, really cool thing about the free conversion of electricity into magnetism and vice-versa is that we can make things DO move, change, act other things at a great distance just by generating and sending electricity to remote locations. The action will travel at speed light, a detail I will explain in a minute. How does electricity make things move at a distance, again? Well, if electricity is magnetic and because magnets can move other things, you can move those things using electricity.
With sufficient sophistication, such actions can be combined with large power sources to reach very far. There, we can replicate anything a human can do with his or her hands: move, stop, grab, release, carry, even fly. You are very familiar with this idea. Any remote controlled vehicle, from a toy car to a military drone uses the trick of turning electricity into magnetism to control and change the state of objects at great distances. The same happens when you turn the wheels, and so forth.
Now, the beauty of electromagnetism is that you can do the reverse to generate electricity. Electricity is the product of moving magnets over or through loops of wire. Kinetic energy physical movement displaces electrons, which carry electric charge, which is captured by the wires, which become electric. In all I said so far I spoke about electromagnetism and electricity as if they were the same thing.
Moreover, I also said that electricity can travel through the air, creating magnetism at a great distance. Your everyday experience tells you, however, that electricity travels through wires. When I say electricity, you might think that I am talking about the power that comes out of an outlet and only about that. At the most, you might allow that I am talking about the power that travels through telephone wires and electronic circuits.
And you were right. But what you did not probably know is radio waves and electric power are in fact the same exact thing. You heard me right. Even more so. Bells, lifting devices, relays, and telegraph sounders use magnets that can be turned on and off.
The second advantage is the added field strength possible with electromagnets. You can detect the presence of a magnetic field around a wire connected to the terminals of a battery. Just dip 53 the wire into a pile of iron filings. See figure Some of the filings will "stick" to the wire as they do the permanent magnets.
Figure Disconnecting one end of the wire from the battery stops the current flow and the filings fall off. When you connect the wire to the battery again, the magnetic effect is restored.
You may observe more of the field about a conductor by sprinkling iron filings on a piece of cardboard through which the conductor passes. Actually, you are observing a cross-section of the magnetic field. This rule is demonstrated in figure In some diagrams of electrical equipment it is necessary to "cut" conductors so that you view them from the ends.
In such cases, it is impossible to use arrows to indicate the direction of current flow. The two drawings at the bottom of figure 49 shows the direction of the field with the "dot" and "cross" system of indicating current flow.
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