Could you explain the concepts behind this question

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I'm trying this question. i know that resistance is the concept of ohms law together with electric potential giving rise to V/I but i can't seem to know how to start. Please advice




A material of resistivity r is formed into the shape of a truncated cone of altitude h. The bottom end has radius b , and the top end has radius a . Assume
that the current is distributed uniformly over any circular cross section of the cone, so that
the current density does not depend on radial position. (The current density does vary
with position along the axis of the cone.) Show that the resistance between the two ends is
described by the expression: R= (density/pi)*(h/ab)
 
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welcome to pf!

hey jimmy! welcome to pf! :smile:

(have a pi: π :wink:)

pretend the cone is a series of very thin discs of height dh :wink:
 
alright thanks! i'll try that
 
To solve this, I first used the units to work out that a= m* a/m, i.e. t=z/λ. This would allow you to determine the time duration within an interval section by section and then add this to the previous ones to obtain the age of the respective layer. However, this would require a constant thickness per year for each interval. However, since this is most likely not the case, my next consideration was that the age must be the integral of a 1/λ(z) function, which I cannot model.
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