Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Vector identity

  1. May 23, 2009 #1
    grad(A*B)=(A*grad)B + (B*grad)A + A curl B + B curl A

    i'm not sure how to read the RHS to begin to work out the index definition.i'm thinking if add and subtract terms this will work out. i think i can see the first two terms, but the last two maybe "A cross nabla" is what they mean acting on B componentwise, otherwise it doesnt mean anything to me.
  2. jcsd
  3. May 23, 2009 #2


    User Avatar
    Homework Helper
    Gold Member

    This is the correct identity:

    ∇(A⋅B) = A⋅∇B + B⋅∇A + A x (∇ x B) + B x (∇ x A)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Vector identity
  1. Product Identity (Replies: 7)

  2. Additive Identity (Replies: 3)

  3. Determinant identity (Replies: 4)

  4. Tricky Identity (Replies: 2)