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What does this - ^ mean when it is over a value?

  1. May 29, 2010 #1
    What does this -- "^" mean when it is over a value?

    The equation for an electric field is E = 1/4pie(epsilon) * Q/r^2 *(^r" I do not know how to put the roof over the r so i put it right next to it")

    What does this value mean because I have also seen it occur with distance. It seems to me like it does nothing for the final answer. What does it do?
     
  2. jcsd
  3. May 29, 2010 #2

    Hurkyl

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    Re: What does this -- "^" mean when it is over a value?

    The hat is a kind of decoration to put on symbols -- it's just another way to vary a symbol, like varying the font or the case or the language.

    One common use for the hat is to indicate the variable represents a unit vector, specifically the normalization of the ordinary vector represented by the same base letter.
     
  4. May 29, 2010 #3

    D H

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    Re: What does this -- "^" mean when it is over a value?

    [tex]\mathbf E = \frac 1 {4\pi\epsilon_0}\,\frac Q{r^2}\hat{\mathbf r}[/tex]

    The electric field is a vector field rather than a scalar field. All of the terms on the right hand side except the final [itex]\hat{\mathbf r}[/itex] are scalars. That final [itex]\hat{\mathbf r}[/itex] is a unit vector that points away from the central charge.
     
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