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  • Apr 29, 2011, 05:08 AM
    ApoorvGoel
    Physics and mathematics
    Q. In maths we use area as a scalar quantity but in physics we use area as a vector quantity?? Why so?
  • Apr 29, 2011, 06:06 AM
    jcaron2

    Where have you seen it as a vector!
  • Apr 29, 2011, 09:16 AM
    Unknown008

    I'm curious about this too...
  • Apr 29, 2011, 12:11 PM
    ApoorvGoel
    Comment on jcaron2's post
    In physics we use area as a vector quantity to solve numerical
  • Apr 29, 2011, 01:00 PM
    ebaines
    Quote:

    Originally Posted by ApoorvGoel View Post
    in physics we use area as a vector quantity to solve numerical

    We're all curious about this - please give an example of where you have seen an area described by a vector in physics. The closest thing I can think of is that the orientation of a plane surface can be described by its orthogonal vector. But that's not its area. Recall that area has units of square meters and no direction, whereas a vector has a unit of length and a direction.
  • Apr 29, 2011, 09:14 PM
    jcaron2

    Yeah, please give a more concrete example. There are certainly plenty of scenarios where one might use a surface integral, integrating over the surface area with respect to some vector normal to that surface, but that's certainly not the same thing as the surface area itself being used as a vector quantity.
  • May 2, 2011, 02:24 PM
    ApoorvGoel
    Comment on ebaines's post
    We use area as a vector quantity in many places such as
    To calculate flux, we say that after doing the dot product of Electric field (vector E) with area (vector A) we get a scalar flux
  • May 2, 2011, 02:33 PM
    ebaines

    No - you're not taking the dot product of the electric field and an area, but rather integrating the dot product of the electric field and the surface normal vector over an area:



    Each differential bit of area dA actually has surface area of 0 in the limit but has a normal direction, hence can be expressed as a vector. That is NOT the same thing as saying that area is a vector.
  • May 2, 2011, 02:41 PM
    ApoorvGoel
    Comment on ebaines's post
    Thanks actually I think my teacher had taught me wrong. Now I will go to him tomorrow and will speak to him about this.

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