Radio waves vs light waves

Okay, here's a weird one for the group: Radio waves are the same as light
waves, except they're not in the visible spectrum, right?

Here's why it matters: As we were departing from Muscatine, IA today (a
beautiful day to fly in the Midwest, BTW -- clear and warm) after a great
lunch, my gaze fell on their on-field VOR transmitter. Focusing closely on
the "Hershey's Kiss"-shaped structure (with my new glasses -- wow, what a
difference a new prescription makes!), I wondered aloud if the lens in my
eye was at that moment focusing powerful radio waves onto my retina.

Mary, a scientist with a strong physics background, was not sure if radio
waves behaved the same as light waves.

I've never heard of anyone frying their retinas by looking at a radio
transmitter, but this begs the question: Can the lens in your eye focus
radio waves?

If not, why not?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay,

a) If you've seen a prism (or the cover of Dark Side of the Moon), you see
that different colors are affected differently when they pass through glass.
The differences if these colors are the wavelength. I suspect eyeglasses are
designed to focus 'average' colored light. I also suspect they will not
focus radio waves.

b) The rods and cones in your eyes are not sensitive to radio waves. (Unless
there's something you're not telling us)


"Jay Honeck" wrote in message
news:%uRYb.353608$na.522124@attbi_s04...
Okay, here's a weird one for the group: Radio waves are the same as light
waves, except they're not in the visible spectrum, right?

Here's why it matters: As we were departing from Muscatine, IA today (a
beautiful day to fly in the Midwest, BTW -- clear and warm) after a great
lunch, my gaze fell on their on-field VOR transmitter. Focusing closely
on
the "Hershey's Kiss"-shaped structure (with my new glasses -- wow, what a
difference a new prescription makes!), I wondered aloud if the lens in my
eye was at that moment focusing powerful radio waves onto my retina.

Mary, a scientist with a strong physics background, was not sure if radio
waves behaved the same as light waves.

I've never heard of anyone frying their retinas by looking at a radio
transmitter, but this begs the question: Can the lens in your eye focus
radio waves?

If not, why not?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Be sure to bring a bottle of that to OSH this summer Jay!
Just kidding.
Ok, here's another weird one... if light is supposed to be made up of both
waves and particles, how much does it weigh? How much resistance do light
particles have on an airplane in flight? Do you have longer range at night?
Does a light bulb weigh more when it's on or when it's off?
--
Jim Burns III

Remove "nospam" to reply

Ok, here's another weird one... if light is supposed to be made up of both
waves and particles, how much does it weigh?

E = mc^2. So a photon (light particle) has an relativistic mass equal
to its energy divided by the speed of light squared. For visible light,
a photon's energy is a few electron-volts (eV)

How much resistance do light
particles have on an airplane in flight?

It has some, yes. Physicists call it "radiation pressure" and it's
measureable in a lab. But in the air it's not much compared to the
pressure due to your average Nitrogen atom which is much more massive
(1,300,000,000 eV of energy).

Do you have longer range at night?
Does a light bulb weigh more when it's on or when it's off?

In a manner of speaking, yes. There's more energy present when the
light bulb's on (in both light and heat), and since energy equals mass
(ala Einstein, above), it does "weigh" more. The extra mass/energy
comes from the wall socket.

To noticably refract radio waves, I think you'd need something with a
thickness at least on the order of the wavelength of the waves. VHF
radio has wavelengths on the order of several meters.

Hope i did all that math right,

--Kath

Holy crap, I knew somebody would know, but now I've got a splitting
headache. I wonder what happens to all the particles of light that can't
make it through windows. Do they pile up on the window sill? Never mind,
my brain hurts

Jim

"Jim" wrote in message
...
Holy crap, I knew somebody would know, but now I've got a splitting
headache. I wonder what happens to all the particles of light that can't
make it through windows. Do they pile up on the window sill? Never mind,
my brain hurts


Particles of light that do not make it through the window and which are not
reflected by the surface are absorbed into the structure. The excess energy
is then radiated away as heat.

The difference between a particle and a wave is the difference between
ripples on the water and the stone you threw in there. The particle is the
object itself. Waves are the measurable effect of the passage of the
particle. It is a fundamental axiom of physics that for very small particles
you can measure either the wave or the particle, but not both
simultaneously. Hence you can look at light as either a wave and measure its
characteristics in that manner, or you can look at where a particular photon
is and measure its characteristics at that moment. The reason is there is
nothing small enough to see both. How would you 'see' a photon, no matter
how much you magnified it? All you can see is where it went.

The light bulb does not create photons. It emits photons that are already
stored in the bulb. It probably absorbs enough electrons in the process so
that its weight does not change significantly.

Particles of light that do not make it through the window and which are not
reflected by the surface are absorbed into the structure. The excess energy
is then radiated away as heat.


Sort of.

They are absorbed, which means the (electromagnetic) energy is converted into
other kinds of energy in the structure, be it raising the orbitals of
electrons, wiggling the atoms around a bit, or accelerating it. The excess
energy is not really "excess" as there is no amount of energy a structure is
"permitted" to have. (not counting enough energy to blow it up. Molecular
motion IS heat. One of the ways energy is dissipated is the ratdiation of
photons (light, be it infra-red or otherwise), another is physical transfer of
momentum (the structure's atoms bounce against air molecules and make the air
molecules go faster). There are more.


The difference between a particle and a wave is the difference between
ripples on the water and the stone you threw in there.


No, the stone and the water are different things. But light, whether thought
of as waves or as particles, is the same thing. And if you think of light as a
particle, you are wrong. If you think of it as a wave, you are also wrong.
That's just the way the universe was put together - it's not my fault. g.


It is a fundamental axiom of physics that for very small particles
you can measure either the wave or the particle, but not both
simultaneously.


True enough.


The reason is there is nothing small enough to see both.


Never thought of it that way, but I don't think it's quite right. I thnk the
reason is more fundamental. "Stuff" is just made of something we don't
understand, and the ways we have though of so far are inadequate when put to
the test, though they make perfect sense in the macroscopic sense.


The light bulb does not create photons. It emits photons that are already
stored in the bulb.


The bulb too does create photons... photons that didn't exist before. It does
so by resisting the motion of electons, and therefore sucking some of their
energy into making the bulb hot, and this releases energy in the form of
photons.

Ok, so just what IS a photon?

Think of an electric field that points up and down, and keeps on switching
directions at some rate. Now think of a magnetic field that points left and
right, but switches directions at the same rate, just a bit out of phase. As
the electric field collapses it generates a magnetic field, and as the magnetic
field collapses it generates an electric field, and the two chase each other at
the speed of light. It's not a perfect description, but it's pretty close to
what a photon is.

It takes energy to make these fields wiggle like that, the energy comes from
the motion of electons in their orbitals. When things happen just right, the
electron collapses, exhausted, back into a lower orbital, and a spurt of energy
in the form of the wiggling Electric and Magnetic fields shoots out. A photon
has been emitted. That's where they come from.

Jose


--
(for Email, make the obvious changes in my address)

"C J Campbell" wrote in message
Particles of light that do not make it through the window and which are
not
reflected by the surface are absorbed into the structure.

So, over the course of time your house gets lighter?

"Katherine" wrote in message
...
Ok, here's another weird one... if light is supposed to be made up of
both
waves and particles, how much does it weigh?

E = mc^2. So a photon (light particle) has an relativistic mass equal
to its energy divided by the speed of light squared. For visible light,
a photon's energy is a few electron-volts (eV)

How much resistance do light
particles have on an airplane in flight?

It has some, yes. Physicists call it "radiation pressure" and it's
measureable in a lab. But in the air it's not much compared to the
pressure due to your average Nitrogen atom which is much more massive
(1,300,000,000 eV of energy).


Still, there has been some research into the idea of using light as means of
propulsion, either in something like solar sails or by using lasers to
bombard objects enough to cause them to move.

Katherine,

Physicists call it "radiation pressure" and it's
measureable in a lab.


you can drive spaceships with it, though. There's a great scifi story
by Arthur C. Clarke about a solar yacht race using radiation pressure
from the sun on big "sails".

--
Thomas Borchert (EDDH)