Missing part in the text of the question. Found the rest on internet:
"<span>determine the resistance for current that passes through the solid in (a) the x direction (b) the y direction and (c) the z direction"
Solution
The relationship between resistance and resitivity is given by
</span>
<span>where R is the resistance
</span>
is the resistivity of the material (for carbon, as in this problem,
)
<span>L is the length of the conductor
A is its cross-sectional area.
We can solve the 3 parts of the problem by using the same formula, but every time L and A will be different (because they will depend on the direction of the current)
(a) the current is in the x-direction, so the length of the conductor is
</span>
<span>while the cross sectional area is
</span>
<span>So the resistance in this case is
</span>
<span>
(b) </span>the current is in the y-direction, so the length of the conductor is
while the cross sectional area is
So the resistance in this case is
(c) the current is in the z-direction, so the length of the conductor is
while the cross sectional area is
So the resistance in this case is