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Thread: Positive and Negative

  1. #61
    Senior Member jegreenwood's Avatar
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    Quote Originally Posted by millionrainbows View Post
    Both voltages exist as "real" values; they are only "positive" or "negative" in relation to each other. You're still stuck in "positive and negative" thinking; those concepts are abstractions. It's all voltage, and it's all real.
    But the relationship of one wave to another makes a difference in the real world. If you have two sound waves with identical amplitudes they will sound different depending on whether they are in phase. If their crests (maximum positive value on the diagram) occur at the same time they will produce a louder sound.

    Fig29.gif

    If the crest of one occurs with the trough (maximum negative value on the diagram) of the other, they will cancel each out - i.e. no sound.

    Fig30.gif

    (images taken from http://www.indiana.edu/~emusic/etext...1_phase2.shtml Chapter 1)

    I, for one, was grateful for this earlier today. This real world relationship allowed me to enjoy Mahler while my air conditioner was running - through noise cancelling headphones.
    Last edited by jegreenwood; Jun-29-2019 at 22:53.

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    Senior Member KenOC's Avatar
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    Quote Originally Posted by millionrainbows View Post
    Both voltages exist as "real" values; they are only "positive" or "negative" in relation to each other. You're still stuck in "positive and negative" thinking; those concepts are abstractions. It's all voltage, and it's all real.
    Not so. If you connect a battery across the terminals of a speaker, the cone will move in or out depending on which way you connected it. If you reverse the battery, the cone will move the opposite direction. It will be the same even in a vacuum.

    In other words, positive and negative in electricity are different and opposite things. They are not defined "in relation to each other" but in relation to a lack of electrical potential entirely.


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    Senior Member millionrainbows's Avatar
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    Quote Originally Posted by KenOC View Post
    Not so. If you connect a battery across the terminals of a speaker, the cone will move in or out depending on which way you connected it. If you reverse the battery, the cone will move the opposite direction. It will be the same even in a vacuum.

    In other words, positive and negative in electricity are different and opposite things. They are not defined "in relation to each other" but in relation to a lack of electrical potential entirely.
    ...they are, themselves, the "potentials" you speak of.

    So, are you saying that if you grabbed a terminal that was carrying -450 volts of direct current voltage, that you wouldn't get shocked?
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    Senior Member RockyIII's Avatar
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    When you strike a timpani with a mallet, the head vibrates back and forth to create the sound, seemingly like a loudspeaker.

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    Quote Originally Posted by millionrainbows View Post
    ...they are, themselves, the "potentials" you speak of.

    So, are you saying that if you grabbed a terminal that was carrying -450 volts of direct current voltage, that you wouldn't get shocked?
    "Voltage" is a very misleading term. Volt is a unit, not a quantity. It is like calling temperature "fahrenheit-age" or "kelvin-age." It is used because the actual name of the quantity is a bit cumbersome, "potential difference," which is short for "electrical potential difference." But the actual name is important.

    The potential difference between point A and point B is the amount of energy needed to move one unit of charge from point A to point B. It is a derived quantity, not a directly measurable physical quantity. In is based the mathematical fact that the amount of energy required to move a charge between two points in an electric field is the same, no matter the path. It is analogous to the fact that it takes the same amount of energy to climb a mountain, regardless of whether you climb directly up the rock face or circle around the back for a more gradual ascent. So if a terminal has a positive potential with respect to the other it is effectively uphill for electrical charge. If the terminal has a negative potential with respect to the other it is effectively downhill from the other. Current flows downhill.

    The result is that you cannot define the potential at a point, except in relation to another point. It can be positive or negative or zero depending on what reference point you choose. So to say a terminal carries -450 volts is meaningless unless you specify -450 volts with respect to what. Probably you mean it carries -450 volts with respect to the other terminal, or ground. Well, if you touch that terminal and you do not touch any other terminal, and you are wearing rubber shoes so you are isolated from ground, you will feel nothing at all. You will only feel something if you touch two terminals that have a potential difference, or if you touch a terminal with a large potential with respect to a ground that you are in contact with.

    When it comes to the positive and negative thing I find it clearer to describe it in terms of current. When current is positive it is flowing from the red terminal to the black terminal (through the speaker). When current it negative it is flows the other way, from the black terminal to the red terminal. That is directly measurable. The wire carrying the current will be deflected in a magnetic field in opposite directions depending on whether current is positive or negative. This establishes the reality of positive and negative signal. (And it is how a loudspeaker works, current is passed through a loop of wire (the voice coil) which is suspended above a strong magnet. The speaker cone moves forward or backward depending on the sign of the current, as described above by KenOC.)
    Last edited by Baron Scarpia; Jul-01-2019 at 17:26.

  6. #66
    Senior Member millionrainbows's Avatar
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    Quote Originally Posted by Baron Scarpia View Post
    "Voltage" is a very misleading term. Volt is a unit, not a quantity. It is like calling temperature "fahrenheit-age" or "kelvin-age." It is used because the actual name of the quantity is a bit cumbersome, "potential difference," which is short for "electrical potential difference."
    That's what I've been telling you all along; it's not a quantity, but a relationship. So I suggest you stop using the term if you wish to make a cogent argument.
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    Senior Member millionrainbows's Avatar
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    Quote Originally Posted by RockyIII View Post
    When you strike a timpani with a mallet, the head vibrates back and forth to create the sound, seemingly like a loudspeaker.
    "Back and forth" is a real direction in time, not an abstraction like "positive/negative."
    "The way out is through the door. Why is it that no one will use this method?"
    -Confucious

    "In Spring! In the creation of art it must be as it is in Spring!" -Arnold Schoenberg

    "We only become what we are by the radical and deep-seated refusal of that which others have made us." -Jean-Paul Sartre

    "I don't mind dying, as long as I can still breathe." ---Me

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    Quote Originally Posted by millionrainbows View Post
    "Back and forth" is a real direction in time, not an abstraction like "positive/negative."
    Back and forth is positive and negative velocity.

    All mathematics is an abstraction. Numbers themselves are an abstraction. Why do you draw the line at negative numbers?
    Last edited by Baron Scarpia; Jul-02-2019 at 17:48.

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    Senior Member millionrainbows's Avatar
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    Quote Originally Posted by Baron Scarpia View Post
    All mathematics is an abstraction. Numbers themselves are an abstraction.
    No, they're not; numbers can embody qualities of the real world. For example, the number 3 can describe the "three-ness" of 3 objects.
    Numbers can also identify things: sheep number 1, sheep number 2, etc.

    You can't have a "zero" sheep, though, or "negative 5" sheep. Those kinds of numbers are abstractions.
    Last edited by millionrainbows; Jul-05-2019 at 17:53.
    "The way out is through the door. Why is it that no one will use this method?"
    -Confucious

    "In Spring! In the creation of art it must be as it is in Spring!" -Arnold Schoenberg

    "We only become what we are by the radical and deep-seated refusal of that which others have made us." -Jean-Paul Sartre

    "I don't mind dying, as long as I can still breathe." ---Me

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    Senior Member jegreenwood's Avatar
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    Quote Originally Posted by millionrainbows View Post
    No, they're not; numbers can embody qualities of the real world. For example, the number 3 can describe the "three-ness" of 3 objects.
    Numbers can also identify things: sheep number 1, sheep number 2, etc.

    You can't have a "zero" sheep, though, or "negative 5" sheep. Those kinds of numbers are abstractions.
    See that's the thing I don't buy. Counting is as much a human concept as negative numbers, irrational numbers etc. It's big distinction is that it's almost certainly the oldest part of the number system. But as I mentioned in an earlier post, there are tribes - I've read about two - who have no concept of "four-ness." Their counting system is 1,2,3, many. As such what we see as - say - 4 and 40, they see as identical.
    Last edited by jegreenwood; Jul-05-2019 at 19:04.

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    Senior Member apricissimus's Avatar
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    Philosophers of a mathematical bent have been wrestling with what the numbers 1, 2, 3, etc., actually are for something like 150 years.

    If you have a good definition of three-ness, I'd love to hear it.

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    Quote Originally Posted by jegreenwood View Post
    See that's the thing I don't buy. Counting is as much a human concept as negative numbers, irrational numbers etc. It's big distinction is that it's almost certainly the oldest part of the number system. But as I mentioned in an earlier post, there are tribes - I've read about two - who have no concept of "four-ness." Their counting system is 1,2,3, many. As such what we see as - say - 4 and 40, they see as identical.
    So if I one of them $40 I could give him $4 and he wouldn’t know the difference?

    If he’s got four kids and his wife has another, does he realise he has more kids than before?
    Last edited by Mandryka; Jul-05-2019 at 21:04.

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  16. #73
    Senior Member jegreenwood's Avatar
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    Quote Originally Posted by Mandryka View Post
    So if I one of them $40 I could give him $4 and he wouldn’t know the difference?

    If he’s got four kids and his wife has another, does he realise he has more kids than before?
    Well I wasn't around at the time, so I don't know the answer to the second (although I could speculate simply kew they had many children to look out for); as for the first, I'm pretty sure they didn't use money.

    And by the way, what does a $10 bill have to do with ten-ness, except in the artificial world of money?

    See also:

    https://www.sciencedaily.com/release...0714111940.htm
    Last edited by jegreenwood; Jul-05-2019 at 21:33.

  17. #74
    Senior Member millionrainbows's Avatar
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    Quote Originally Posted by jegreenwood View Post
    Well I wasn't around at the time, so I don't know the answer to the second (although I could speculate simply kew they had many children to look out for); as for the first, I'm pretty sure they didn't use money.

    And by the way, what does a $10 bill have to do with ten-ness, except in the artificial world of money?
    Okay, so you've completely removed number from anything real, and now you want me to "prove" it for you? Hurrah for abstraction.
    "The way out is through the door. Why is it that no one will use this method?"
    -Confucious

    "In Spring! In the creation of art it must be as it is in Spring!" -Arnold Schoenberg

    "We only become what we are by the radical and deep-seated refusal of that which others have made us." -Jean-Paul Sartre

    "I don't mind dying, as long as I can still breathe." ---Me

  18. #75
    Senior Member millionrainbows's Avatar
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    Quote Originally Posted by apricissimus View Post
    Philosophers of a mathematical bent have been wrestling with what the numbers 1, 2, 3, etc., actually are for something like 150 years.

    If you have a good definition of three-ness, I'd love to hear it.
    You want definitions? You're actually arguing with such an obvious reality? I think you're over-thinking this.
    "The way out is through the door. Why is it that no one will use this method?"
    -Confucious

    "In Spring! In the creation of art it must be as it is in Spring!" -Arnold Schoenberg

    "We only become what we are by the radical and deep-seated refusal of that which others have made us." -Jean-Paul Sartre

    "I don't mind dying, as long as I can still breathe." ---Me

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