Current density, resistance and resistivity problem

AI Thread Summary
A problem involving a 10.71 V battery connected to a resistive strip with three sections of different conductivities raises questions about current density and conservation of charge. The discussion highlights that the current density is assumed to be equal across the sections, prompting inquiries about the basis for this assumption. One participant struggles with calculating current density for the third section and finds discrepancies in the conductivities of the first two sections. The confusion stems from misreading graph values, specifically the scale factor of x10^3 instead of x10^-3. Ultimately, the participant resolves the issue by correcting their interpretation of the graph values.
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In a problem it states that:

A 10.71 V battery is connected to a resistive strip that consists of three sections with the same cross-sectional areas but different conductivities.

In the solution to the problem it stipulates that the current density of the three sections are equal. Where in the above statement does it imply that.
 
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please answer guys
 
Think about what the definition of current density is. Also, is current conserved?
 
charge and current are reserved.

I am also working on this problem, but when I calculate the current density from the third section (since I am given the third section's conductivity) I am getting the wrong answer for the conductivities of parts 1 and 2..

charge density = conductivity of part 3 * electric field of part 3

J = \sigma * E3

The current of the battery flows through the 3 part resistive strip to the negative terminal of the battery.

the distance on the strip is defined as 0 at the positive connection side of the strip and 9.12mm at the negative side of the strip.

I then use the equation

conductivity = J / E per part

to calculate conductivity of parts 1 and 2.

Im getting this wrong so I am guessing calculating J is wrong. Can someone steer me in the right direction?
 
I figured it out!

I was reading the graph values wrong in that it was x10^3 and not x10-3
 

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