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Old Mar 10th 2014, 01:12 PM   #11
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Is a radio-signal (Electro-magnetism) made by sending a current up and down an aerial? What process makes us able to recieve the signal again? And you wrote that the sun generates photons, how does it do it? Thanks.
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Old Mar 11th 2014, 11:37 AM   #12
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In a metal some of the electrons in the atom are only rather loosely ascociated with the atom.
They are fairly free to roam from one atom to the next.
Apply a small push and one can get a significant number to move.
(This is an electrical current).

In the transmitter this push is given by the applied voltage difference.
In the reciever, this push is applied by the passing radio wave.

The resultant movement of electrons in the aerial of the reciever is rather tiny,
which is why significant amplifiers are (usually) added to radios.
(it is possible to make a very simple radio without an amplifier, look up "crystal sets", but the resultant sound level is low).

When two hydrogen atoms are thrown together at ridiculously high speeds,
they will fuse to create helium.
The "binding" energy of the nucleus of a helium atom is less than the binding energy of two hydrogen nuclei.
The energy difference is released (largely) as photons.

The energy released is substantial, and much work has ben done to try to harness this process on the Earth.
However the speed at which the atoms have to move are huge,
the sort of speeds that occur in the centre of a nuclear bomb (or in the centre of the sun).
It is just about possible to build machines to get to these speeds,
but the amount of energy fed in to reach these speeds is much higher than the amount of energy produced by the tiny amount of fusion achieved.

It is hoped that improved fusion machines will eventually produce more energy than they consume,
but that still apears to be quite a ways in the future.
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Old Mar 11th 2014, 12:16 PM   #13
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What do you mean by that «The "binding" energy of the nucleus of a helium atom is less than the binding energy of two hydrogen nuclei»? So, a reciever work in the way that the fotons of the electromagnetic radiovawe pushes the electrons and creates a current in it? Can you explain why some chemical processes makes certain substanses give off electrons? What is a circuit ? Where do the electrons end up? Thanks
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Old Mar 12th 2014, 11:47 AM   #14
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How Far do you want to go...

Binding energy is just the energy involved in binding the constitent bits of an atom together.

I have been trying to think of analogies that could be utilised for imaging the interaction of charged particles:

Consider a speed boat racing round and round a buoy.
As it completes a circuit it meets the wake it created on the previous circuit.
At certain speeds and circuit diameters, the wake will be difficult to drive into,
at other speeds and circuit diameters, the wake will be easy to drive into.

A moving electron also produces an electromagnetic wake.
In an atom some orbits of the electron around the nucleous will work, others won't, as the electron encounters its own wake.
(It is a bit more complicated because the orbits are 3 dimensional)

All chemical reactions involve electrons.
Returning the the boat analogy, imagine a number of boats racing around a pair of buoys.
For some boats the wake interactions form nice stable orbits around one or the other buoy.
For boats further out, the best orbits circle both buoys.
It is the electrons circling both nuclei that hold molecules together.

The analogy starts to break down now.
Some atoms have electron orbits where the "outer" electrons are barely held in what may be considered uncomforatable orbits.
Other atoms have potential orbits available where an extra electron could easily be accommodated.

Put one of each type together and they will "share" an electron.
Some chemicals share the electron fairly equally, others almost completely take over the "shared" electron.

A circuit is simply a conductive route around which electrons can pass,
idealy doing something useful on the way.
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Old Mar 17th 2014, 02:39 PM   #15
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Lightbulb

So in a circuit, does the electrons go back to the same material they left from? And when they create heat in an resistance, what makes that heat? And perhaps you could explain what Voltage and Ampere is also? You also said what makes the light from the Sun is «When two hydrogen atoms are thrown together at ridiculously high speeds» What makes the hydrogen atoms move so fast in the Sun? This is the last questions I have for you, I don't want to take up to much of your time: What is engergy ? Thanks a lot.
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Old Mar 19th 2014, 10:33 AM   #16
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In a circuit, individual electrons are unlikely to get back to where they started.
A better way to visualise it is that there are electrons queuing all around the circuit.
The battery (for example) pushes electrons into the queue at one end and pulls them off at the other.
In the middle all the other electrons shuffle along to maintain an even spacing in the queue.

Heat is the movement of the atoms.
The atomic nuclei can be imagined as sitting embedded in an electron foam
as the electrons in this foam move, they consequently cause turbulence which causes the nuclei (and hence the atom) to move, which is heat.

Heat is the movement of the atoms.
It is ridiculously hot in the center of the Sun, so the atoms are moving ridiculously fast.
Being at the centre of the Sun, they are also being squeezed together by the huge gravity of the Sun, which helps encourage the fusion.

What is Energy, I will leave to others...
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