How are electricity and magnetism related?
Any moving electric charge creates a magnetic field. Thus, if you have a wire with no current flowing through it, there is no overall field (though electrons moving around atoms still make tiny tiny ones). But once electrons start moving through it, you get a field around the wire. That's essentially what electromagnets take advantage of. This works in reverse, too. A magnetic field can exert a force on electrically charged particles moving through it. Stationary particles are unaffected. This is essentially how the Earth's magnetic field protects us from cosmic rays.
Are electricity and magnetism the same thing?
No, but they are considered opposing sides of the same coin, co-existing together. Scottish physicist James Clerk Maxwell published a unifying theory of electricity and magnetism in 1865. Maxwell's equations go into great scientific detail, of course one needs to be able to understand them. The short simple answer is that a changing electric field has an associated magnetic field and a changing magnetic field induces an electric field.
How is magnetism related to electricity?
They are not distinct. There is only one thing, electromagnetism.Others have discussed how one can create the other, so I’ll just point out a significant result from special relativity.Observers moving relative to one another will split space and time in different ways. Some of what one sees as space the other will see as time and vice versa. You can see this mixing in the Lorentz transformations.A similar relationship exists between electricity and magnetism — different observers moving relative to one another will characterize what is electric and what is magnetic differently. There is an analog to the Lorentz transformations to quantify this.So the lesson is the same in both cases. There is not space and time, there is only spacetime. Similarly, there is not electricity and magnetism, there is only electromagnetism.On reflection, I should add that some people have claimed you can derive magnetism from electrostatics via the transformation properties of the fields. This is not, in fact, correct. It isn’t hard to show that there is no frame in which a pure electric field can be seen as a pure magnetic field or vice versa. You need the whole thing as a fundamental beast.
How are all electromagnetic waves alike?How are they different?
Electromagnetic waves are made out of photons. So electromagnetic waves are all essentially a form of light. The frequency of the electromagnetic wave is what differentiates it from others.
Electricity and magnetism seem different, but electricity can create magnetism, and magnetism can create electricity. How is this done in real life applications?
Transformers, electric engines and generators, Antennas of every kind all work on the same principle.Magnetism is around a wire where a current flows. Wind it up in a coil and you’ll multiply it.Voltage pops out when a variable filed or a a relative motion exist on a conductor. Wind it up and you will multiply it.The simple case are transformers: two coils couple two circuits with different “multipliers”.Another case are engines: A current producing a field is used to produce a force on another interacting current. When a movement exist, voltages also pops out, producing other currents that add up.Similarly in antennas, variable currents and voltage produce variable magnetic and electric fields that self sustain across space
Is direction of electric field and magnetic field always the same?
The question needs to be clearer. Is the direction of electric and magnetic field always the same as what? Same as each other? Same with respect to to source charges? Same with respect to different observers?A general electric or magnetic field has different directions at different points in space and time depending on the position and motion of the source charges. Electric and magnetic fields of the same source charge distribution are perpendicular to each other at every point. Electric and magnetic fields due to different sources can have arbitrary orientation with respect to one another. Beyond this the question in its current state can't be answered more accurately.
How are the electric field and the magnetic field related by the special theory of relativity?
In classical physics, electric fields arise from electric charge, and magnetic fields arise from electric currents—that is, moving electric charge.It’s the “moving” part that’s the hook to special relativity. There’s a “frame of reference” that sees the charge as moving (hence creating a magnetic field), and other frame of reference in which the charge is moving differently (and thus creating different fields).How, then, can these different different points of view come to the same predictions? Motion in special relativity causes other effects, like “Lorentz contraction” of distance. When these are taken into account, the points of view end up being the same. In other words, what observers in one frame of reference call “magnetic” observers in another frame of reference might call “electric,” but in the end, the motions that these effects cause are the same.Simple example: Consider a long, straight wire. When there’s no current in the wire, there’s a linear density of electron charge carriers (negative charge per meter) and a linear density of nuclei (positive charge per meter) that are equal and opposite. In other words, in total, there’s no net charge per meter. A stationary test charge near the wire feels no force. Now, let the electrons in the wire move as an electric current. Again, a stationary test charge outside of the wire feels no force because—even though the electrons are moving—the linear charge densities of the positive and negative charges are still equal and opposite. However, if the test charge were to be moving parallel to the current (with velocity v), it would feel a force (towards or away from the wire). In one point of view (“our” frame of reference), that’s because the current creates a magnetic field B, and v x B results in a force. However, in the frame of reference of the test particle, v=0. But in addition, both the nuclei and the electrons are moving. And since they’re moving, they’re Lorentz contracted (or in the case of the electrons, perhaps less so if the test charge moves in the direction of the current). This means that their charge per meter is different—and more to the point, the positive and negative charges per meter are no longer equal and opposite. So, there’s an “electrostatic” (rather than “magnetic”) force (towards or away from the wire). And yes, if you actually apply the theories quantitatively to this situation, the magnitude of the force comes out to be the same—which is quite amazing.