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Electrostatics - Coulomb's Law

by jinksys
Tags: coulomb, electrostatics
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jinksys
#1
Feb26-12, 05:59 PM
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P: 123
I'm doing example 2.1 in Griffith's Electrodynamics book. Can someone explain where the cos(theta) comes from in the formula for dE? The formula is on the first image: Here.
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jinksys
#2
Feb26-12, 06:20 PM
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P: 123
SOLVED:

I see what's going on. If you add the r_hat vectors you end up with 2(z/r)z_hat. z/r=cos(theta). So we end up with 2cos(theta)z_hat.
bael
#3
Feb26-12, 06:32 PM
P: 28
that looks so hard. are you supposed to figure out that formula all by yourself

jinksys
#4
Feb26-12, 06:37 PM
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P: 123
Electrostatics - Coulomb's Law

Quote Quote by bael View Post
that looks so hard. are you supposed to figure out that formula all by yourself
No, the formula is given to you in a general form.


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