LinkBack URL
About LinkBackswhy can't be induced current with light(moving electromagnetic field) in closed circular loop with coil?
June 6th, 2007, 07:14 AM
why can't be induced current with light(moving electromagnetic field) in closed circular loop with coil?
It happens. This is the principle of the antenna. Electromagnetic radiation strikes the antenna and induces a current of the same frequency. The antenna may be a coil, a straight wire, a parabolic dish (as a reflector), or be of virtually any other configuration.
For communication purposes the transmitting beam must generally be of a single phase. The problem with using sunlight, for example, is that it consists of a great many beams, all out of phase with each other. Induced currents all cancel.
What do you mean by this phase with each other?Originally Posted by SteveF
A wave consists of a series of peaks and valleys, or positive and negative peaks. If the positive peaks of two parallel waves coincide, we say they are "in phase." If a positive peak coincides with a negative peak we say they are completely "out of phase." And of course all in-between conditions are possible.
This link might give you a better understanding:
http://csunix1.lvc.edu/~snyder/1ch6.html
Â*
Can't understand. Can you tell me it with simpler words? Thank you. Why the induced currents are canceled?
That's due to something called "destructive interference."Can't understand. Can you tell me it with simpler words? Thank you. Why the induced currents are canceled?
Hopefully, you know what a wave looks like when it's graphed and has a reference line running horizontally across it's middle - a series of peaks and slopes and valleys just as another poster described.
Anything above the baseline (center) is given a positive value and the parts below are considered negative.
When two waves are considered together, you add their values algebraically - meaning a positive and another positive ( like +2 and +2) add together (and make +4 in this example). But if one is a +2 and the other is a -1 the result would be a -1. And a +2 and a -2 two would completely cancel each other out with a result of 0 (zero).
Did that help or would a picture be more helpful? I trust that you do understand algebraic addition, right?
How is possible that some waves are positive and some negative!? How do I know that some waves are positive and some negative?That's due to something called "destructive interference."Can't understand. Can you tell me it with simpler words? Thank you. Why the induced currents are canceled?
Hopefully, you know what a wave looks like when it's graphed and has a reference line running horizontally across it's middle - a series of peaks and slopes and valleys just as another poster described.
Anything above the baseline (center) is given a positive value and the parts below are considered negative.
When two waves are considered together, you add their values algebraically - meaning a positive and another positive ( like +2 and +2) add together (and make +4 in this example). But if one is a +2 and the other is a -1 the result would be a -1. And a +2 and a -2 two would completely cancel each other out with a result of 0 (zero).
Did that help or would a picture be more helpful? I trust that you do understand algebraic addition, right?
We can try a simple picture. You have a flashlight but one of its two batteries is reversed. You get no light and you cannot detect any current in the circuit. That is because the effect of the two batteries is to cancel each other. We might say their voltages are completely out of phase,
And do the electrons move inside of the batteries? I sow your comments and understand something from the pictures. But can't understand why the waves cancel each other. Isn't the light moving electromagnetic field? The fields are canceling or what?
No, you misunderstand. It's not that the waves themselves are positive or negative, it's that we assign those values to components (parts) of the wave for very practical common purposes - many, many purposes in fact. Anything to do with dealing with electricity, electronics and light and many other things.
Perhaps a picture will help. Here's one of two sine waves.
Note the thin gray line across the middle (called the x-axis). Everything above that line is assigned positive values and everything below it is assigned negative values. Although the numbers are little blurred in this picture, they run from zero at the middle up to a positive 2 on the top and a negative 2 on the bottom. They are marked off in increnemts of 1/2. The waves shown have maximum values of plus and minus 1.
Does that make things any better?[/img]
And do the electrons move inside of the batteries? I sow your comments and understand something from the pictures. But can't understand why the waves cancel each other. Isn't the light moving electromagnetic field? The fields are canceling or what?
scientist91, I'm sorry if this is too personal but how old are you and how far along in school are you? That would help me a great deal in understanding how to best explain what you are asking about.
Thanks
Answer of this question, I can't find anywhere. So I am just asking you. What does it metter if they are not in phase? The magnetic fields are canceling or what? THank you very much for your efforts.
You're very welcome. I'd like to help more but it appears I'm having difficulty in explaining.Answer of this question, I can't find anywhere. So I am just asking you. What does it metter if they are not in phase? The magnetic fields are canceling or what? THank you very much for your efforts.
Yes, the electromagnetic fields cancel. The positives are added to the negatives and if they are equal the result is zero - they completely cancel each other out.
and do in one moving direction light, the waves are moving in reverse direction? Two waves can be canceled right? But what will happen if they cancel?You're very welcome. I'd like to help more but it appears I'm having difficulty in explaining.Answer of this question, I can't find anywhere. So I am just asking you. What does it metter if they are not in phase? The magnetic fields are canceling or what? THank you very much for your efforts.
Yes, the electromagnetic fields cancel. The positives are added to the negatives and if they are equal the result is zero - they completely cancel each other out.
Anyone have the answer? "and do in one moving direction light, the waves are moving in reverse direction? Two waves can be canceled right? But what will happen if they cancel?"
It doesn't matter which way they are moving. If they completely canel each other nothing is left. Zero is zero.
So there is no light when they cancel right? But I think that is not the matter why there is not induced current.It doesn't matter which way they are moving. If they completely canel each other nothing is left. Zero is zero.
Of course it matters. When there is zero - nothing - there cannot be induced anything. Nothing is zero is nothing.So there is no light when they cancel right? But I think that is not the matter why there is not induced current.It doesn't matter which way they are moving. If they completely canel each other nothing is left. Zero is zero.
Seriously, I cannot tell where you are trying to go with this. Whenever two waves of any kind - electromagnetic, water, sound or whatever completely cancel each other out, there's nothing left over. And nothing can only do nothing. It's the same as if they never were there in the beginning.
So when they cancel also there is no light right?Of course it matters. When there is zero - nothing - there cannot be induced anything. Nothing is zero is nothing.So there is no light when they cancel right? But I think that is not the matter why there is not induced current.It doesn't matter which way they are moving. If they completely canel each other nothing is left. Zero is zero.
Seriously, I cannot tell where you are trying to go with this. Whenever two waves of any kind - electromagnetic, water, sound or whatever completely cancel each other out, there's nothing left over. And nothing can only do nothing. It's the same as if they never were there in the beginning.
Yes, that's right.So when they cancel also there is no light right?Of course it matters. When there is zero - nothing - there cannot be induced anything. Nothing is zero is nothing.So there is no light when they cancel right? But I think that is not the matter why there is not induced current.It doesn't matter which way they are moving. If they completely canel each other nothing is left. Zero is zero.
Seriously, I cannot tell where you are trying to go with this. Whenever two waves of any kind - electromagnetic, water, sound or whatever completely cancel each other out, there's nothing left over. And nothing can only do nothing. It's the same as if they never were there in the beginning.
I asked physicist he told me that there is no current because of the high frequency? What is the roll of the frequency?
Perhaps I'm begining to understand what you are asking (you don'r kane it very easy.) :wink:
Are you wanting to induce an electric current in a wire by shining a light beam on it?
Yeah!Perhaps I'm begining to understand what you are asking (you don'r kane it very easy.) :wink:
Are you wanting to induce an electric current in a wire by shining a light beam on it?
Then I'm very sorry. It's just as the physicist told you - the frequency of visible is light is MUCH to high for that! You would have to use a photovoltaic cell (commonly called a solar cell) to do that. Photons will simply not interact with ordinary wire of any type other than slightly heat it in direct sunlight.Yeah!Perhaps I'm begining to understand what you are asking (you don'r kane it very easy.) :wink:
Are you wanting to induce an electric current in a wire by shining a light beam on it?
What happens with the electrons?Then I'm very sorry. It's just as the physicist told you - the frequency of visible is light is MUCH to high for that! You would have to use a photovoltaic cell (commonly called a solar cell) to do that. Photons will simply not interact with ordinary wire of any type other than slightly heat it in direct sunlight.Yeah!Perhaps I'm begining to understand what you are asking (you don'r kane it very easy.) :wink:
Are you wanting to induce an electric current in a wire by shining a light beam on it?
What electrons - the ones in the wire when the light strikes it? Nothing happens to them. Do you perhaps mean some other electrons?What happens with the electrons?Then I'm very sorry. It's just as the physicist told you - the frequency of visible is light is MUCH to high for that! You would have to use a photovoltaic cell (commonly called a solar cell) to do that. Photons will simply not interact with ordinary wire of any type other than slightly heat it in direct sunlight.Yeah!Perhaps I'm begining to understand what you are asking (you don'r kane it very easy.) :wink:
Are you wanting to induce an electric current in a wire by shining a light beam on it?
Yes the electrons in the wire? Are they moving when the light strikes the wire?What electrons - the ones in the wire when the light strikes it? Nothing happens to them. Do you perhaps mean some other electrons?What happens with the electrons?Then I'm very sorry. It's just as the physicist told you - the frequency of visible is light is MUCH to high for that! You would have to use a photovoltaic cell (commonly called a solar cell) to do that. Photons will simply not interact with ordinary wire of any type other than slightly heat it in direct sunlight.Yeah!Perhaps I'm begining to understand what you are asking (you don'r kane it very easy.) :wink:
Are you wanting to induce an electric current in a wire by shining a light beam on it?
No.Yes the electrons in the wire? Are they moving when the light strikes the wire?What electrons - the ones in the wire when the light strikes it? Nothing happens to them. Do you perhaps mean some other electrons?What happens with the electrons?Then I'm very sorry. It's just as the physicist told you - the frequency of visible is light is MUCH to high for that! You would have to use a photovoltaic cell (commonly called a solar cell) to do that. Photons will simply not interact with ordinary wire of any type other than slightly heat it in direct sunlight.Yeah!Perhaps I'm begining to understand what you are asking (you don'r kane it very easy.) :wink:
Are you wanting to induce an electric current in a wire by shining a light beam on it?
Why not?No.Yes the electrons in the wire? Are they moving when the light strikes the wire?What electrons - the ones in the wire when the light strikes it? Nothing happens to them. Do you perhaps mean some other electrons?What happens with the electrons?Then I'm very sorry. It's just as the physicist told you - the frequency of visible is light is MUCH to high for that! You would have to use a photovoltaic cell (commonly called a solar cell) to do that. Photons will simply not interact with ordinary wire of any type other than slightly heat it in direct sunlight.Yeah!Perhaps I'm begining to understand what you are asking (you don'r kane it very easy.) :wink:
Are you wanting to induce an electric current in a wire by shining a light beam on it?
Because they aren't affected. Two things happen when light strikes the wire - some of it is reflected away and some of it is absorbed causing heating.Why not?No.Yes the electrons in the wire? Are they moving when the light strikes the wire?What electrons - the ones in the wire when the light strikes it? Nothing happens to them. Do you perhaps mean some other electrons?What happens with the electrons?Then I'm very sorry. It's just as the physicist told you - the frequency of visible is light is MUCH to high for that! You would have to use a photovoltaic cell (commonly called a solar cell) to do that. Photons will simply not interact with ordinary wire of any type other than slightly heat it in direct sunlight.Yeah!Perhaps I'm begining to understand what you are asking (you don'r kane it very easy.) :wink:
Are you wanting to induce an electric current in a wire by shining a light beam on it?
Neither of those does anything to the electrons.
Why do you think it should? As the physicist and I both explained to you, the frequency is MUCH too high for that to happen. Light shines on many kinds of conductors - copper, aluminum, steel, etc. without disturbing one single electron.Why not?No.Yes the electrons in the wire? Are they moving when the light strikes the wire?What electrons - the ones in the wire when the light strikes it? Nothing happens to them. Do you perhaps mean some other electrons?What happens with the electrons?Then I'm very sorry. It's just as the physicist told you - the frequency of visible is light is MUCH to high for that! You would have to use a photovoltaic cell (commonly called a solar cell) to do that. Photons will simply not interact with ordinary wire of any type other than slightly heat it in direct sunlight.Yeah!Perhaps I'm begining to understand what you are asking (you don'r kane it very easy.) :wink:
Are you wanting to induce an electric current in a wire by shining a light beam on it?
Once again, the effect you are looking for only happens in the very special materials used to make solar cells. And not wire of any kind.
| « Kinetic Energy Storage | From which side the electrons move to? » |
| Bookmarks |
Bookmarks |
