Light and Radio Waves

[mezarashi]

This is something you probably have noticed, but if you have an incoming call while your mobile phone is close to some speakers, you will hear some jitter in the speakers, which can get relatively violent depending on their quality and magnetic shielding.

 

You can conclude that the presence of strong electromagnetic fluctuations in the radio frequency range will induce electrical fields in the electrical-magnetic system. The question is (knowing that light and radiowaves are both electromagnetic waves simply of different frequencies), why is it that if you shine visible light, infared, or UV light onto the speakers, you will definitely get no response, even if the light is so intense it will melt the speakers away. This is suggesting that there is some special "cut-off" frequency in which electromagnetic waves no longer can induce currents in the speakers.

[CPL.Luke]

no, look up the photovoltaic effect

 

Edit:

 

The higher the frequency of the light, the more energy the exiting electrons will have. The greater the intensity of the light, the more electorns will be scattered. your detector might not be looking at the higher energy electrons.

[mezarashi]

I suppose you mean the photoelectric effect of light striking a metal surface? Well, I'm not referring to that experiment, rather a real life case with what we see as electromagnetic interference with our electronic equipment. This "electromagnetic" seems to be limited to electromagnetic waves of the radio frequency. My question is why so.

[CPL.Luke]

higher frequency light (visual spectrum) is stopped by the plastic around your phone.

 

same effect

[swansont]

I suppose you mean the photoelectric effect of light striking a metal surface? Well, I'm not referring to that experiment, rather a real life case with what we see as electromagnetic interference with our electronic equipment. This "electromagnetic" seems to be limited to electromagnetic waves of the radio frequency. My question is why so.

 

 

At RF, the electronics still "looks" like an antenna. In the visible, which is ~ a million times higher in frequency and shorter in wavelength, it does not.

[H2SO4]

maybe im just not smart enough to understand what your exactly talking about, but the simplest reason id think is becuase light is composed of photons, and radiowaves are made of whatever...electromagnetic radiation. keywordword: electromagnetic

 

 

 

From what i understand photons dont have any electrical properties.

[CPL.Luke]

yes they do, radio waves are light, light covers all electromagnetic radiation.

 

also there is no such thing as the magnetic force

[mezarashi]

maybe im just not smart enough to understand what your exactly talking about' date=' but the simplest reason id think is becuase light is composed of photons, and radiowaves are made of whatever...electromagnetic radiation. keywordword: electromagnetic

 

From what i understand photons dont have any electrical properties.[/quote']

 

Ah, but this is exactly what I'm focusing on. Light IS electromagnetic radiation. A photon can be considered radio, infared, visible, UV, or gamma depending on its energy, E = hf which is a function of frequency.

 

So considering that both light and radio waves are fundamentally the same thing, why is it that one causes interference while the other doesn't. On the plastic covering note, I'm sure that the effect will be the same no matter how bare you expose your system. Shine some visible light onto an antenna. It will probably heat it up but not induce any electrical current. But expose it to a strong radio source and surely you will get electrical currents oscillating at the radiation's frequency. I'd like to explore more on swansont's comment about what makes something "look" like an antenna.

 

[Additional: Nice picture from googling on the electromagnetic spectrum]

[[Tycho?]]

Something like light has a great deal more energy than radio waves. As such, where light waves are absorbed by atoms when an electron goes up a quantum level (im not sure if this is the correct terminology), radio waves do not have the energy to do this, and will not be absorbed as readily. So light is easier to absorb than the radio waves, which is why the radio waves can travel through things like walls to reach your radio inside the house.

 

This also depends on the antenna. Certain lengths of antennae can absorb certain wavelengths of radio waves. I dont really know much about the relationship though, but talk to swans more about it, since it is very true that light would need a much MUCH smaller antenna than radio waves.