Electromagnetic radiation

[rthmjohn]

Visible light is packets of photons. The only difference between visible light and the rest of the spectrum is frequency and wavelength. Does this mean that all electromagnetic radiation is comprised of photons?

[swansont]

Visible light is packets of photons. The only difference between visible light and the rest of the spectrum is frequency and wavelength. Does this mean that all electromagnetic radiation is comprised of photons?

 

Yes, though you might not always be in a situation where you notice the particle nature of the radiation, and instead notice the wave nature.

[5614]

All forms of electromagnetic radiation is comprised of photons, whether you have your long wavelength (low frequency) radio waves or your high frequency gamma rays or the somewhere in between visible light, it's all forms of the same thing. As you correctly said the only difference is wavelength/frequency.

 

An equation you can do is that the:

 

speed of a wave = frequency x wavelength

 

now for electromagnetic radiation

 

speed = speed of light, c

 

so

 

c = frequency x wavelength

 

as c is constant then you are saying that when frequency goes up wavelength must go down.

 

So if frequency x wavelength always equals the same number, c, then you can see if frequency goes up wavelength must go down and vice versa, so the two are indirectly proportional, ie. one goes up the other goes down and that relationship between them is proportional.

[dorcus]

I would also like to add that Electromagnetic Radiation with a wavelength between 400 nm and 700 nm can be detected by the naked eye, and is percieved as visible light.

[rthmjohn]

Thanks. It makes sense that if all electromagnetic radiation moves at the speed of light then it should be comprised of photons.

[ecoli]

yep, that reasoning is sound.

[5614]

The only other thing I can think of that moves at the speed of light would be gravity.

 

Everything else is slower than c.

[dorcus]

uh huh... i can't think of anything either.. anybody know of anything else?

[mezarashi]

There are few things that naturally travel at the speed of light. Electric fields and gravitational fields also propagate at the speed of light. Light can be considered a disturbance in the field and disturbances also travel at the speed of light.

[CuriousMan]

Is photon a partical that has positive or negative charge,or no charge at all or it is just an energy that is invisable?

[[Tycho?]]

Is photon a partical that has positive or negative charge,or no charge at all or it is just an energy that is invisable?

 

 

They do not have a charge.

[Severian]

The only other thing I can think of that moves at the speed of light would be gravity.

 

Everything else is slower than c.

 

Gluons (for the strong interaction) also travel at c.

[Mobius]

neutrinos (if they have no mass). Only massless particles can travel at the speed of light.

 

The question over neutrinos mass is debatable, Fermi proposed it was massless but modern theories suggests it does have a very small amount of mass.

[5614]

Scientists now agree that neutrinos DO have a mass and thus they do not travel at c.

[CuriousMan]

Thank you. I have already found the answer to my question myself. Photon is quantum, it is not a particle but just electro-magnetic energy.