- #1
abdo375
- 133
- 0
How does Electromagnetic waves travel in vacuum ?
actionintegral said:I don't think there is a fundamental reason for this. Your question can be replaced with "Why does a coulomb field expand through space?". "Why does a gravitational field travel through space". It simply does.
You can consider an EM wave in terms of a disturbance in the electromagnetic field, but it isn't a 'real' thing, in the sense that it's the photon you observe and detect, not the field it represents.
HallsofIvy said:It is just a wave in the electromagnetic fields of charged particles that permeates everything- even vacuum.
abdo375 said:ZapperZ,first, could you please recommend some books for me discussing this topic?
The problem is that this question popped into my head during an Antenna lecture and when I asked the professor about it, he had no explanation, although he told me that he'll look it up I now doubt that he will find anything -since he's an EE and your saying that it needs QED for the explanation- but because I'm considering doing my master's in EM I would really like to understand why this happens.
actionintegral said:abdo375, you did not take my answer seriously. There are certain phenomena that are not currently explicable in terms of more fundamental concepts. Here is an example:
Q: Why does proper time slow down for a moving person?
A: Because the speed of light must be constant.
Q: Why must the speed of light be constant?
A: No one knows. That is a postulate.
You will look at an antenna, conclude that the EM waves propagate because of the oscillations of the electrons, then you will learn about displacement current and then you will ask "but why does it propagate at all in the first place?" And you will re-derive my answer.
abdo375 said:I find it very hard to accept somethings in this world as it is, without an explanation.
actionintegral said:Q: Why does proper time slow down for a moving person?
A: Because the speed of light must be constant.
Q: Why must the speed of light be constant?
A: No one knows. That is a postulate.
An electromagnetic wave travels through a vacuum by oscillating electric and magnetic fields that are perpendicular to each other and to the direction of travel. These fields are created by the acceleration of charged particles, such as electrons, in an antenna or other source.
The speed of an electromagnetic wave in a vacuum is equal to the speed of light, which is approximately 3 x 10^8 meters per second (m/s). This value is a fundamental constant of the universe and does not change.
The wavelength of an electromagnetic wave in a vacuum is inversely proportional to its frequency. This means that as the frequency increases, the wavelength decreases, and vice versa. This relationship is described by the equation c = λν, where c is the speed of light, λ is the wavelength, and ν is the frequency.
Yes, electromagnetic waves can travel through other media, such as air, water, and even solid objects. However, the speed of the wave will be different in each medium, as it is affected by the properties of the medium, such as density and temperature.
Electromagnetic waves in a vacuum differ from other types of waves, such as mechanical waves, in that they do not require a medium to travel through. They can also travel at the speed of light, which is much faster than the speed of sound for mechanical waves. Additionally, electromagnetic waves can travel through a vacuum, while mechanical waves cannot.