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Thread: electromagnetic radiation..

  1. #1 electromagnetic radiation.. 
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    I was wondering why the sunlight is called the electromagnetic radiation.
    Is it because the.. i don't know.. aka somekind of the property of both magnetic and the electrical effects if not what may be the reasons...

    Can quantum mechanic explain this or can the simple laws of electromagnetism explain it..i did not fine anyclue on this site
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  3. #2 Re: electromagnetic radiation.. 
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    Quote Originally Posted by newspaper
    I was wondering why the sunlight is called the electromagnetic radiation.
    Is it because the.. i don't know.. aka somekind of the property of both magnetic and the electrical effects if not what may be the reasons...

    Can quantum mechanic explain this or can the simple laws of electromagnetism explain it..i did not fine anyclue on this site
    http://www.physics-physicsdiscussion.blogspot.com
    Light from the sun is electromagnetic radiation, (or gamma radiation, all electromagnetic radiation is called gamma radiation) that arises from when a moving electric current produces and magnetic field and when a moving magnetic field creates an electric current. Light is one part of the EM (electromagnetic) spectrum, it is of the frequency is in nm, (Newton metres).



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    Willmer's notes are good. You don't need quantum mechanics to appreciate the electro-magnetic nature of light. This wiki article (if you scroll down far enough), talks about how the electro-magnetic nature of light was revealed.

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  5. #4 Re: electromagnetic radiation.. 
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    Light from the sun is electromagnetic radiation, (or gamma radiation, all electromagnetic radiation is called gamma radiation) that arises from when a moving electric current produces and magnetic field and when a moving magnetic field creates an electric current. Light is one part of the EM (electromagnetic) spectrum, it is of the frequency is in nm, (Newton metres).
    Thanks for the reply but i wanted to know why is the light from the sun called the electromagnetic radiation..And where does the moving electric current occur.

    Maxwell Could well quote " let there be current and magnet and there is light" I don't understand this too??
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  6. #5 Re: electromagnetic radiation.. 
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    Quote Originally Posted by newspaper
    Thanks for the reply but i wanted to know why is the light from the sun called the electromagnetic radiation..And where does the moving electric current occur.

    Maxwell Could well quote " let there be current and magnet and there is light" I don't understand this too??
    Electrons in the atom cause electromagnetic radiation as it moves inwards towards the nucleus after being pushed away by contributed energy, if I'm not mistaking.

    That's the short version
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  7. #6 Re: electromagnetic radiation.. 
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    Quote Originally Posted by newspaper

    Light from the sun is electromagnetic radiation, (or gamma radiation, all electromagnetic radiation is called gamma radiation) that arises from when a moving electric current produces and magnetic field and when a moving magnetic field creates an electric current. Light is one part of the EM (electromagnetic) spectrum, it is of the frequency is in nm, (Newton metres).
    Thanks for the reply but i wanted to know why is the light from the sun called the electromagnetic radiation..And where does the moving electric current occur.

    Maxwell Could well quote " let there be current and magnet and there is light" I don't understand this too??
    Radiation means, 'energy that is exhibited by a body'. Electromagnetic means 'energy exhibited from electicity and magnetism'. Its called electromagnetic because the moving electric current within the Sun creates a magnetic field, and vice versa. If the sun's electric current or magnetic field did not move, they'd stay the same and would not combine to make electromagnetism, therefore there would be no EM radiation. To get EM radiation you need there to be a moving electric current or magnetic field to combine into each other before it is possible.

    The moving electric current comes from the suns core (this is the theory), which has certain elements within it that are good conductors of electricity (moving electrons), this means that there is a current running. This current in the sun moves inside the sun, as it moves it creates magnetism. The two together make electromagnetism. EM radiation is light, Ultra violet , infra red etc. A particle of light is created when an electron 'jumps' from one part of the atom to another (I won't get technical here), but its called 'Quantum leaping'. When these electrons are moving between atoms (electricity), they move within the atoms they are in and as a result-give of particles of EM radiation (called photons).

    A moving electric current occurs in the sun by the sun rotating. If you got a lab current made from batteries and moved that, you'd have a magnetic field established. Ever noticed that ear phones for the ipod or any general music player eventually become magnets? That very reason. If you need any more help, I'm here. All knowing in the realm of time travel!
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  8. #7 Re: electromagnetic radiation.. 
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    Quote Originally Posted by svwillmer
    Quote Originally Posted by newspaper

    Light from the sun is electromagnetic radiation, (or gamma radiation, all electromagnetic radiation is called gamma radiation) that arises from when a moving electric current produces and magnetic field and when a moving magnetic field creates an electric current. Light is one part of the EM (electromagnetic) spectrum, it is of the frequency is in nm, (Newton metres).
    Thanks for the reply but i wanted to know why is the light from the sun called the electromagnetic radiation..And where does the moving electric current occur.

    Maxwell Could well quote " let there be current and magnet and there is light" I don't understand this too??
    Radiation means, 'energy that is exhibited by a body'. Electromagnetic means 'energy exhibited from electicity and magnetism'. Its called electromagnetic because the moving electric current within the Sun creates a magnetic field, and vice versa. If the sun's electric current or magnetic field did not move, they'd stay the same and would not combine to make electromagnetism, therefore there would be no EM radiation. To get EM radiation you need there to be a moving electric current or magnetic field to combine into each other before it is possible.

    The moving electric current comes from the suns core (this is the theory), which has certain elements within it that are good conductors of electricity (moving electrons), this means that there is a current running. This current in the sun moves inside the sun, as it moves it creates magnetism. The two together make electromagnetism. EM radiation is light, Ultra violet , infra red etc. A particle of light is created when an electron 'jumps' from one part of the atom to another (I won't get technical here), but its called 'Quantum leaping'. When these electrons are moving between atoms (electricity), they move within the atoms they are in and as a result-give of particles of EM radiation (called photons).

    A moving electric current occurs in the sun by the sun rotating. If you got a lab current made from batteries and moved that, you'd have a magnetic field established. Ever noticed that ear phones for the ipod or any general music player eventually become magnets? That very reason. If you need any more help, I'm here. All knowing in the realm of time travel!
    Thanks once again but one more thing ,do you intend to say that, like how the air is the medium for the sound to travel electromagnetic field creates a sort of the field for the light to pass. If this is so i have learned that light does not need any medium to travel. And you asserted that the particle is created when electron jumps and it called "quaantum leaping"

    and is it only me that do not understand quantum..ahhha mechanics.
    "www.physics-physicsdiscussion.blogspot.com" i tried reading this post manier time but i did not find the term "quantum leaping"
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  9. #8  
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    Thanks once again but one more thing ,do you intend to say that, like how the air is the medium for the sound to travel electromagnetic field creates a sort of the field for the light to pass.
    The light is the electromagnetic field. Spacetime itself is the medium through which the field can propagate. The electric, and magnetic permittivities of free space (vacuum) are two properties of spacetime that affect the transmission of this field. Not entirely sure of the details here, but they somehow dictate the speed of light too I think?
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  10. #9  
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    Quote Originally Posted by bit4bit
    Thanks once again but one more thing ,do you intend to say that, like how the air is the medium for the sound to travel electromagnetic field creates a sort of the field for the light to pass.
    The light is the electromagnetic field. Spacetime itself is the medium through which the field can propagate. The electric, and magnetic permittivities of free space (vacuum) are two properties of spacetime that affect the transmission of this field. Not entirely sure of the details here, but they somehow dictate the speed of light too I think?
    Do you mean that light it self is an electromagnetic field. why does this not happen to sound to. Sound should also propagate in it own field
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  11. #10  
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    Sound should also propagate in it own field
    Sound is made up of the medium that it is traveling through. Areas of higher and lower density traveling through a medium.
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  12. #11  
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    Sound and light are completely different. Light is an electromagnetic field, whereas sound is actually a wave of pressure throughout the medium - it is actually made up of pressure variations within the medium (air for instance).

    Consider a loudspeaker. when a pulse of current is sent into the speaker, the solenoid pulls on the magnet, causing the 'skin' of the speaker to move. The movement of the skin affects the air molecules around it. Those molecules directly in contact with the speaker will move, then they will collide with others, which in turn will collide with othrs, etc... effectively producing a wave of air pressure. The amount the speaker moves determines frequency and amplitude.

    We can then detect these sounds with our ears because the pressure wave will 'hit' our eardrum causing it to vibrate at a certain amplitude and frequency. Then nerves somehow measure this change and the sound is registered by your brain.

    Therefore, sound cannot travel when there is an absence of matter.

    Light can travel through a complete vacuum, because electric, and magnetic fields need not depend on the presence of fluid (or matter). If you want to try and visualise a medium for the fields, then just think in terms of spacetime itself (the fabric of the universe) being the medium. As I mentioned before there is a direct connection between the two.
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  13. #12  
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    Quote Originally Posted by bit4bit
    Sound and light are completely different. Light is an electromagnetic field, whereas sound is actually a wave of pressure throughout the medium - it is actually made up of pressure variations within the medium (air for instance).

    Consider a loudspeaker. when a pulse of current is sent into the speaker, the solenoid pulls on the magnet, causing the 'skin' of the speaker to move. The movement of the skin affects the air molecules around it. Those molecules directly in contact with the speaker will move, then they will collide with others, which in turn will collide with othrs, etc... effectively producing a wave of air pressure. The amount the speaker moves determines frequency and amplitude.

    We can then detect these sounds with our ears because the pressure wave will 'hit' our eardrum causing it to vibrate at a certain amplitude and frequency. Then nerves somehow measure this change and the sound is registered by your brain.

    Therefore, sound cannot travel when there is an absence of matter.

    Light can travel through a complete vacuum, because electric, and magnetic fields need not depend on the presence of fluid (or matter). If you want to try and visualise a medium for the fields, then just think in terms of spacetime itself (the fabric of the universe) being the medium. As I mentioned before there is a direct connection between the two.
    Thanks bit4bit now i am understanding the nature of the electromagnetic radiation a little. If you don't mind can you tell me something more about the electromagnetic radiation coming in the discrete form not continous.
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  14. #13  
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    Well light in its discrete form is referred to as 'photon particles' which are discrete packets (or 'quanta') of energy. The funny thing is, that light can be both continuous and discrete at the same time, as described by quantum mechanics.

    If you look at the 'Dual split experiment' you will see what I mean.

    Basically you have a monochromatic (single wavelength) light source shining through two parallel, narrow slits in a board, and on to a screen that is coated with a light detecting chemical. When a single slit is open, the light shines through it and appears as a narrow band of dots on the screen. (Each dot represents a single photon striking it). This is pretty much what you'd expect.

    However when both slits are open, you actually get an interference pattern on the screen, indicating that light coming through each slit has been diffracted, and interfered with the other causing the striped interference pattern. This can only happen if the light is a wave, and yet on the screen we still detect the light as discrete dots, indicating , that light itself is made up of discrete 'quanta'.

    The same thing happens if you fire electrons or atoms at the screen, and surprisingly it also works if you fire the particles one at a time, so that the seemingly contradictory result cannot just be some complex effect of a collection of particles, but actually dictates that individual particles are both a wave, and a discrete particle simultaneously.
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