haganmc
Show that an infinite line of charge with linear charge density lamda exerts an attractive force on an electric dipole with magnitude F = (2)(Lamda)(p) / (4)(pie)(Epsilon knot)(r^2). Assume that r is much larger than the charge separation in the dipole.
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This Question is Closed
haganmc
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What part of this is the answer?
haganmc
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I don't understand what the answer is
Algebraic!
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start with the field of an infinite line of charge, what is that?
haganmc
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E= 1/(4pi€.) * ( 2(lambda))/r. Then what do I do?
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differentiate and multiply by p :)
haganmc
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How would I differentiate? By dx?
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did you look over the "force on a dipole" section?
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Is the derivation clear?
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r
haganmc
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Yes. I think. Lol
haganmc
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Do I differentiate or integrate?
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differentiate that upside down triangle is the gradient (space derivative)
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here everything only depends on r, no x's y's or z's needed to characterize the problem...
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so the gradient is just the derivative with respect to r
haganmc
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Differintiating will get rid of r
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nope. r is the variable.
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what's the derivative of 1/r with respect to r?
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\[-1/r ^{2}\]
haganmc
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Okay I got it. Is the final answer suppose to be negative?
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all the rest of the terms are constants, they stay unchanged... multiply by the dipole moment (p) and you're done...
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yes negative r hat is towards the center so it's an attractive force...
haganmc
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Oh now it makes sense thank you so much!! I may pass my quiz tomorrow now!
Algebraic!
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Hope it helped:) gl on the quiz!
haganmc
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Thanks