What's the difference between radio and magnetic waves?

[ofosot69]

I need to know what is the difference between an electromagnetic wave and a radio wave?

I came to know that frequencies below 3 kHz are electromagnetic waves but are they photos or something else?

If an iron core coil rod is connected with a frequency oscillator and AC is applied to the coil from 100 Hz to 2 MHz then till 3 kHz the coil will behave like an electromagnet but not after that?

After 3 kHz, photos will radiate from the coil in the form of radio waves?

 

[danadak]

FAQ section here that may help :

Electromagnetic waves: Definition, Propagation, and Types

Find out about electromagnetic waves. What are their characteristics and sources. Learn the mechanism of propagation of EM waves along with a few examples.

www.sciencefacts.net

Electromagnets generally done with DC, eg. attract/repel depending on polarity.
Applying AC is a continuous train of attract/repel and not useful as an electromagnet.

Regards, Dana.

 

[crutschow]

After 3 kHz, photos will radiate from the coil in the form of radio waves?

The frequency has nothing to do with whether the radiated signal is a radio (electromagnetic) wave or not (in the form of photons).

Any AC current will radiate electromagnetic waves.
Whether that wave is practically detectable, depends upon the frequency, current, and configuration of the wire containing that current.

Any current also has an associated close (near) magnetic field which is independent of frequency (going down to DC).

 

[Pommie]

I love the fact that Maxwell described the propogation of electromagnetic waves as having a constant speed (c) even though, at the time, no one understood how this was possible.

Mike.

 

[crutschow]

I love the fact that Maxwell described the propogation of electromagnetic waves as having a constant speed (c) even though, at the time, no one understood how this was possible.

Mike.

Yes, it was amazing that, using just the known equations for electric and magnetic fields at the time, he combined them, which then predicated the generation of electromagnetic waves traveling near the then known approximation for the speed of light.
It took more than 20 years after that before Hertz was able to experimentally build an apparatus that could generate and detect them (other than light). He was also able to determine that the speed of those waves was close to speed of light.
Interestingly, Hertz was not very forward-looking about his discovery, since when asked what those EM waves could be used for he replied "Nothing, I guess".