Also, why you can produce radio waves with a simple amplifier circuit and a piece of wire, but need special devices like an LED or a discharge tube to produce light?
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>but you can produce and receive one with a simple metal rod (antenna) and only the other can be focused with glass lens
Because different parts of the electromagnetic spectrum interact with different materials in different ways. Glass blocks UV and infrared but is transparent to every other part of the spectrum. Wood blocks visible light but is transparent to everything else.
>Also, why you can produce radio waves with a simple amplifier circuit and a piece of wire, but need special devices like an LED or a discharge tube to produce light
This is just wrong. You most certainly do not need a LED or discharge tube to produce light. What do you think incandescent lightbulbs are? I mean hell, what do you think fire is? Is that not light? You can make light from a piece of wood. That’s much simpler than an amplifier circuit.
>but you can produce and receive one with a simple metal rod (antenna) and only the other can be focused with glass lens
Because different parts of the electromagnetic spectrum interact with different materials in different ways. Glass blocks UV and infrared but is transparent to every other part of the spectrum. Wood blocks visible light but is transparent to everything else.
>Also, why you can produce radio waves with a simple amplifier circuit and a piece of wire, but need special devices like an LED or a discharge tube to produce light
This is just wrong. You most certainly do not need a LED or discharge tube to produce light. What do you think incandescent lightbulbs are? I mean hell, what do you think fire is? Is that not light? You can make light from a piece of wood. That’s much simpler than an amplifier circuit.
If you pump enough current through a metal rod it will be hot as hell and start glowing red and releasing visible light. I’m also guessing you could make an antenna out of something that is a good conductor but not a metal like carbon fiber.
Light can be “received” by a lot of things that aren’t glass lenses, it is just not useful for us to extract meaningful information from them.
Radio and light are electromagnetic light. That means that they can influence the electrons in something conductive. However, in order for the effect to be very strong, the conductive thing needs to be on a similar scale to the wavelength of the waves. The shortest radio waves start at a few millimeters and go up to kilometers. Their scale is in the range of things we can see and hold.
Visible light has wavelengths on a scale similar to largish molecules. Molecules with a lot of double bonds can act like wires or antennas. Look up the structure of carotenoids, and you’ll see why the absorb light and give vegetables distinct colors. The length of the molecule determines the wavelengths that it can absorb.
Carrots have color because the molecules are acting like antennas at the right wavelength of light. Different length molecules will give different colors.
So TLDR, it’s because the wavelength needs to be close to the size of the antenna and visible light is way too small.
The electromagnetic wave goes up and down, with peaks and troughs. The peaks and troughs of the electromagnetic waves are closer together the higher the frequency. The distance between the peaks and troughs is called “wavelength”. Different wavelengths makes waves behave differently for different materials.
A radio wave can be produced from an antenna because the peaks and troughs of a wave at that frequency are on a human scale. In order to produce one, you push and pull the electric field on a piece of wire that’s on the scale of the wavelength you’re producing, and you get a transmission. 300 Megahertz, for example, has a wavelength of 1 meter. FM Radio, which is on the order of ~ 100 MHz, has a wavelength of about 3 meters. WIFi has a wavelength of about 12 cm.
Light, on the other hand, has a wavelength on the order of hundreds of nanometers, a billionth of a meter. At this scale of wavelength, the wave behaves totally differently, and you can’t use the “push-pull” trick to produce a signal as easily anymore, because your antenna would have to be very small.
If you pump enough current through a metal rod it will be hot as hell and start glowing red and releasing visible light. I’m also guessing you could make an antenna out of something that is a good conductor but not a metal like carbon fiber.
Light can be “received” by a lot of things that aren’t glass lenses, it is just not useful for us to extract meaningful information from them.
>but you can produce and receive one with a simple metal rod (antenna) and only the other can be focused with glass lens
Because different parts of the electromagnetic spectrum interact with different materials in different ways. Glass blocks UV and infrared but is transparent to every other part of the spectrum. Wood blocks visible light but is transparent to everything else.
>Also, why you can produce radio waves with a simple amplifier circuit and a piece of wire, but need special devices like an LED or a discharge tube to produce light
This is just wrong. You most certainly do not need a LED or discharge tube to produce light. What do you think incandescent lightbulbs are? I mean hell, what do you think fire is? Is that not light? You can make light from a piece of wood. That’s much simpler than an amplifier circuit.
Radio and light are electromagnetic light. That means that they can influence the electrons in something conductive. However, in order for the effect to be very strong, the conductive thing needs to be on a similar scale to the wavelength of the waves. The shortest radio waves start at a few millimeters and go up to kilometers. Their scale is in the range of things we can see and hold.
Visible light has wavelengths on a scale similar to largish molecules. Molecules with a lot of double bonds can act like wires or antennas. Look up the structure of carotenoids, and you’ll see why the absorb light and give vegetables distinct colors. The length of the molecule determines the wavelengths that it can absorb.
Carrots have color because the molecules are acting like antennas at the right wavelength of light. Different length molecules will give different colors.
So TLDR, it’s because the wavelength needs to be close to the size of the antenna and visible light is way too small.
The electromagnetic wave goes up and down, with peaks and troughs. The peaks and troughs of the electromagnetic waves are closer together the higher the frequency. The distance between the peaks and troughs is called “wavelength”. Different wavelengths makes waves behave differently for different materials.
A radio wave can be produced from an antenna because the peaks and troughs of a wave at that frequency are on a human scale. In order to produce one, you push and pull the electric field on a piece of wire that’s on the scale of the wavelength you’re producing, and you get a transmission. 300 Megahertz, for example, has a wavelength of 1 meter. FM Radio, which is on the order of ~ 100 MHz, has a wavelength of about 3 meters. WIFi has a wavelength of about 12 cm.
Light, on the other hand, has a wavelength on the order of hundreds of nanometers, a billionth of a meter. At this scale of wavelength, the wave behaves totally differently, and you can’t use the “push-pull” trick to produce a signal as easily anymore, because your antenna would have to be very small.
If you pump enough current through a metal rod it will be hot as hell and start glowing red and releasing visible light. I’m also guessing you could make an antenna out of something that is a good conductor but not a metal like carbon fiber.
Light can be “received” by a lot of things that aren’t glass lenses, it is just not useful for us to extract meaningful information from them.
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