- #1
carlosbgois
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Homework Statement
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The total force on a moving charge q with velocity v is given by [tex]\mathbf{F}=q(\mathbf{E}+\mathbf{v}\times\mathbf{B})[/tex] Using the scalar and vector potentials, show that [tex]\mathbf{F}=q[-\nabla\phi-\frac{d\mathbf{A}}{dt}+\nabla(\mathbf{A}\cdot\mathbf{v})][/tex]
Homework Equations
[/B]
(1) [tex]\mathbf{E}=-\frac{d\mathbf{A}}{dt}-\nabla\phi[/tex]
(2) [tex]\mathbf{B}=\nabla\times\mathbf{A}[/tex]
(3) [tex]\mathbf{v}\times(\nabla\times\mathbf{A})=\nabla(\mathbf{v}\cdot\mathbf{A})-\mathbf{A}(\mathbf{v}\cdot\nabla)[/tex]
The Attempt at a Solution
[tex]\mathbf{F}=q(\mathbf{E}+\mathbf{v}\times\mathbf{B})=q[-\nabla\phi-\frac{d\mathbf{A}}{dt}+\mathbf{v}\times\mathbf{B}][/tex]
Now I need to show that
[tex]\mathbf{v}\times\mathbf{B}=\nabla(\mathbf{A}\cdot\mathbf{v})[/tex]
I tried applying (3) but didn't know where to go from there.