If light is made up of photons, but X-rays and ultraviolet etc are not, but they are all the electromagnetic spectrum, when does there stop being photons? Do the boundaries of visible light (violet and red) have less photons than the other colours?
>when does there stop being photons?
What? Explain what you mean here.
>>7961692
I apologise if my wording is wrong
What I'm trying to say is, visible light is made up of photons yes? That's what we're taught, but we're also taught that it's part of the electromagnetic spectrum, and I'm assuming that X-rays and ultraviolet and microwaves are not all made up of photons, yet the visible light is.
I'm lost on where it stops being made up of photons and starts being made up of something else
>>7961685
>X-rays and ultraviolet etc are not
They are
>>7961700
I should elaborate, everything on the EM spectrum is light, you're thinking of visible light which is just the stuff we can see.
>>7961700
Really?
How come X-rays can penetrate things that visible light can't? :/
>>7961685
>but X-rays and ultraviolet etc are not
All of the different regions (gamma, x-ray, UV, visible, infrared, radio) are all electromagnetic radiation and all of them contain photons. They are ALL light. The different regions are artificial boundaries.
>>7961704
Because they are a higher frequency, that's all that defines different kinds of light. Different frequencies can do different things, higher frequency light is generally better at travelling through dense materials.
>>7961704
geeeez... really...
Thet say history repeats itself but this?
https://www.reddit.com/r/askscience/comments/1p4cai/if_photons_are_smaller_than_atoms_why_dont_they/
>>7961712
Can you please explain?
Surely if a photon is too big to pass through matter at a low frequency such as visible light, why does a higher frequency increase it's penetration?
>>7961715
I'm really sorry is that a recent thread? I had no idea this was just a question that's been buzzing round my head for a while
>>7961715
Thanks for linking this btw, that really helps clear things up
>>7961685
There is no end to photons. As long as there is light there are photons. The suns not only emits photons with wavelengths of visible light, it also emits light with gamma rays, x-rays, infrared, microwaves and radiowaves. I tried to order it off the top of my head by smallest wavelength to largest wavelength. My bad if i messed up. There is also a range of wavelengths and range of frequencies.
>>7961718
You must be new here or highly educated...
never the less....
NEVER APOLOGIZE....
>>7961727
Why do we have wavelength and frequency, if the wavelength decreases won't the frequency increase and vice versa? Or is there something I'm missing out?
>>7961729
Definatly the first, I'm just some curious guy with a dumbass physics teacher that couldn't explain
>>7961717
It's not to do with how "big" the photon is, in fact at that level the concept of size doesn't really make a lot of sense. There are a number of ways to explain why higher frequency light passes through things. One loose way of thinking about it that I find satisfying and that I think isn't horrendously wrong is that when light gets absorbed by a physical barrier the energy it carries dissipates into the medium (usually because it's a conductor), therefore light with higher frequency can pass further through materials because it can lose more energy without depleting completely.
>>7961750
Okay, so you're saying that when the energy is absorbed the frequency lowers, or does a higher frequency wave just have more energy?
>>7961735
Yes.
[math]\mathrm c = \lambda \cdot \nu[/math], with c as speed of light, [math]\lambda[/math] as wavelength and [math]\nu[/math] as frequency.
>>7961763
I'm sorry I didn't understand any of that, are you saying that you can have a high frequency and a long wave length due to some third variable? Thanks
>>7961712
You got it backwards. Lower frequency is more penetrating.
>>7961772
Yeah, the frequency and wavelength are related to each other. The higher the frequency, the smaller the wavelength and vice versa.
Regarding >>7961754 the Energy depends directly on the wavelength or frequency.
[math]E = \mathrm h \cdot \nu = \frac {\mathrm {h \cdot c}} \lambda[/math], where [math]E[/math] is the energy and h is the Planck constant.
>>7961754
No the amplitude (intensity) of the light lowers as it travels through a medium that absorbs light, the frequency does change once it goes into the new medium but that's to do with the fact that the speed of light is different in different materials.
As for the frequency energy relation, that's where photons come in, the energy of a photon is
[eqn]e=h \nu[/eqn]
where [math]\nu[/math] is frequency and [math]h[/math] is Planck's constant.
It gets a bit weird here because up until now I've been talking about light as waves and for a wave the energy is just to do with the amplitude of the wave but in the photon view it's to do with the frequency. The view you choose generally depends on the problem you're looking at, generally for a lot of light passing through some material on the macroscopic level the wave picture is fine but for things happening at smaller levels the photon view becomes more useful.
>>7961772
Frequency times wavelength gives the speed of a wave and since the speed of light in constant then a higher wavelength means a lower frequency.
>>7961785
Oops, that should really be a capital E in that equation
>>7961778
Huh yeah that's right, I'm misremembering stuff.
Reading back up on it a bit more I think it's actually just due to the higher frequency light generally having higher energy per photon that allows it to pass through stuff so easily.
Well guys, as per usual when I ask a question about Physics...
I'm more confused than when I started, but about different stuff, thanks guys :D
>>7961723
That diagram applies more to sound. Low frequency sound penetrates/vibrates structures that high F sound won't.
What an interesting thread. Makes me 'think' about a received classroom fact. Nice.
Here is my take on it.... Electricity. If you heat a wire it's resistance increases. The reasoning is that the heat excites the atoms in the wire, thus, because they are moving around more, it makes for a more 'dense' path for the current to flow through.
Turn this thinking on its head. The higher frequency wave/photon has more chances of passing through a material (by being able to bypass the atoms easily) than the lower frequency.
I hope you idiots are trolling in here. Lower frequency waves are better at penetrating objects than higher frequency waves. Think: UV light doesn't even go through glass, light does. Light doesn't go through walls, radio waves do.
>>7962619
What about x-rays? What about gamma radiation?
Both very high frequency, both penetrate.
