- #1
arl146
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Homework Statement
At what distance along the central axis of a ring of radius R = 0.200 m and uniform charge is the magnitude of the electric field due to the ring's charge maximum? What is the positive solution for z?
Homework Equations
E = [itex]\frac{kqz}{(z^2+R^2)^(3/2)}[/itex]
The Attempt at a Solution
I know I should differentiate that above equation with respect to z and then set it equal to 0 to get z but i just don't know how to differentiate that ..
E = [itex]\frac{kqz}{(z^2+R^2)^(3/2)}[/itex]
the k and the q are held as constants and can be taken out of the differentiation ..
= kq*[[itex]\frac{d}{dz}[/itex]((z2+R2)3/2]
isn't [itex]\frac{d}{dz}[/itex]((z2+R2)3/2 = -3z(z2+R2)^(-5/2) ??
so it would be kq [-3z(z2+R2)^(-5/2)]
but that doesn't work for when you set it = 0. what am i supposed to be doing that I am not