I'm looking at this question: http://i.imgur.com/7TsHH.png?1
I'm thinking about Ohm's Law, but I feel like I don't have enough information.
Any ideas?
Thanks!
I'm thinking about Ohm's Law, but I feel like I don't have enough information.
Any ideas?
Thanks!
-
The simpilist way is to note that E is the negative gradient of the voltage;
E = - dV/dL
And since the voltage is obvously linear w.r.t to the length you can find the gradient as;
dV/dL = (Vf - Vi)/(xf - xi) = (6 - -4)/(.1 - 0) = 100 v/m
E = - 100 v/m (the negative means the direction of E is toward lower voltage)
You can also start with Ohm's Law in terms of E and current density J as;
E = (1/D)J = (1/D)(i/A) = (1/D)(V/RA) = (1/D)(V/pLA/A) = V/L
where D = 1/p , conductivity = 1/resistivity
The negative doesn't show up because its a magnitude calculation.
E = - dV/dL
And since the voltage is obvously linear w.r.t to the length you can find the gradient as;
dV/dL = (Vf - Vi)/(xf - xi) = (6 - -4)/(.1 - 0) = 100 v/m
E = - 100 v/m (the negative means the direction of E is toward lower voltage)
You can also start with Ohm's Law in terms of E and current density J as;
E = (1/D)J = (1/D)(i/A) = (1/D)(V/RA) = (1/D)(V/pLA/A) = V/L
where D = 1/p , conductivity = 1/resistivity
The negative doesn't show up because its a magnitude calculation.